Weird bug in MS Project 2003 Resource Leveling

A

Andre

Dear all,

i observe some very strange behaviour of the leveling algorithm of the
MS Project 2003 and would appreciate any ideas on how to fix it.

MS Project Info
------------------------
MS Project Professional 11.0.2003.0816.15

Steps to reproduce a bug
------------------------

1. Create new project

2. Create tasks

Id Task Duration Start End
Predec Ressources
1 T1 5 days Mon 26.12.05 Fri 30.12.05 A
2 T2 5 days Mon 26.12.05 Fri 30.12.05 B
3 T3 5 days Mon 26.12.05 Fri 30.12.05 4SS A
4 T4 5 days Mon 26.12.05 Fri 30.12.05 B

3. Set Prio of Task T1 and T2 to 520, Set Prio of Tasks T3 and T4 to
500

3. Run "Level resources" with "Day by day", Leveling Order "Standard,
Priority"

Following dates are calculatesd

Id Task Duration Start End
Predec Ressources
1 T1 5 days Mon 26.12.05 Fri 30.12.05 A
2 T2 5 days Mon 26.12.05 Fri 30.12.05 B
3 T3 5 days Mon 09.01.06 Fri 13.01.06 4SS A
4 T4 5 days Mon 02.01.06 Fri 06.01.06 B

Task T3 begins on 09.01.06 and not as expected on 02.01.06.


Andy
 
J

Jan De Messemaeker

Hi Andre,

Yes, weird and yes, a bug.
From my tests here it seems that when you change places 3-4 (in such a way
that the SS arrow points down, 3SS as a predecessor on 4) that leveling
works properly.
Hope this helps,
 
A

Andre

Hi Jan,

Thanks a lot for your reply and your suggestion!

Unfortunately it would not help, because in reality task 4 tends to
start later as task 3. The intention of the planed constraint would be
to delay task 3 till task 4 starts.

Changing the constraint to "Task 4 starts only after Task 3 starts" as
you suggest would be without effect in that case.

Do you have an idea which is the process for communicating such bugs on
Project-team at Microsoft?

Thanks,
Andre
 
J

JulieS

Hi Andy and Jan,

I was unable to reproduce the error. I am running MS Project Pro 2003 SP-2.

I *believe* I have followed your setup instructions Andy, and the results I
get are:

Task 1 Start: 26 Dec 2005 Finish: 30 Dec 2005
Task 2 Start: 02 Jan 2006 Finish: 06 Jan 2006 Leveling Delay: 7
edays
Task 3 Start: 02 Jan 2006 Finish: 06 Jan 2006 Leveling Delay: 7
edays
Task 4 Start: 26 Dec 2005 Finish: 30 Dec 2005

I'm afraid I don't have any explanation as to why I am getting the results
you expected -- even with repeated attempts.

Andy, are you running SP-2?

Hope this helps.

Julie
 
A

Andre

Hi Julie,

Thanks a lot for your test! I run SP1, i hope that is the reason. I
will install SP2 and give feedback if it helps.

Andy
 
J

Jan De Messemaeker

Hi,

I hope SP2 brings relief but if not...
I'm afraid you didn't read my soolution slowly enough
I said
A. MOVE BOTH TASKS such that 4 becomes 3 and 3 becomes 4
B. Now the same LOGCAL link is 3-4SS and works well on leveming.

HTH
 
A

Andre

Hi Jan,
Hi Julie,

unfortunately upgrade to SP2 have not helped.

@Jan: do i understand correct that you suggest the following

Pos Task Dur Start
End Pred Res
1 T1 5 Tage Mo 26.12.05 Fr 30.12.05 A
2 T2 5 Tage Mo 26.12.05 Fr 30.12.05 B
3 T4 5 Tage Mo 26.12.05 Fr 30.12.05 B
4 T3 5 Tage Mo 26.12.05 Fr 30.12.05 3AA A

if so, it does not help, because after leveling i receive the following
:

Pos Task Dur Start
End Pred Res
1 T1 5 Tage Mo 26.12.05 Fr 30.12.05 A
2 T2 5 Tage Mo 26.12.05 Fr 30.12.05 B
3 T4 5 Tage Mo 02.01.06 Fr 06.01.06 B
4 T3 5 Tage Mo 09.01.06 Fr 13.01.06 3AA A

As you see, Task T3 begins on 09.01.06


Nevertheless, thanks for your time!

Andy
 
J

Jan De Messemaeker

Hi,

Right you are!
I don't remember how I could have thought this morning that it helped, I
must have also changed the priorities.
If you link the 2 B tasks FS all's well..
HTH
 
T

Trevor Rabey

Congratulations Andre.
There must be a big finder's fee to go with this.
I wish I had discovered a real bug.

Putting them back to:
T1 5d A
T2 5d B
T3 5d A 4SS
T4 5d B

If you add the 2FS link at T4, and then level, OK, T3 ES = 02/01
If you force T4 to Must Start On 02/01, and then level, OK, T3 ES = 02/01.
If you do either and then take them off and then level again it goes bad
again, T3 ES = 09/01.
So, any way that T4 gets forced to 02/01, except levelling, makes/allows the
4SS link work OK.(?)

This is a tiny glitch and rarely encountered in practice, but unnerving.
As well as a good argument for ensuring every Task has at least 1 FS
predecessor, and a strict minimum of all other types, which is good advice
anyway, it's a bug.
Is it a leveling bug or a linking bug?
The linking works ok if there is no leveling, so it must be a leveling bug,
but it only happens with this link.
If leveling is set to manual, and other calculation automatic, then leveling
can only happen when you push the button.
If then leveling does something else (mysterious), as well as "delay Tasks
to remove Resource over-allocation", then I will not be able to advise
students/clients etc that "Leveling is simple. Leveling delays Tasks to
remove Resource over-allocation, and nothing more", which is also very
common advice on this NG.

The levelling delay of T3 and T4 both stay at 7 Edays, even when T3 is
scheduled for ES = 1 week later than necessary!

You have to admit, this is disconcerting at least for anyone making a living
out of MSP, and erodes the faith of the faithful and members of the MSP fan
club who have to teach this stuff and defend MSP from the people who say it
is crap and P3 is better.
I must remember this one for next time the MSP spruiker is making the big
pitch and demo at the software show or the PMI chapter meeting. No, that
would be unnecessarily cruel.
Is there any chance MS is going to fess up on this;-) ?

This goes on the very short list of real bugs along with allowing the the
pilot/aircraft tp take off separately and the ALAP type sucking all of the
float out of its successors, not so much a bug, no matter how annoying, but
more a missing feature, which goes on the very short list of real missing
features (eg Zero Total Float Constraint, Zero Free Float Constraint,
Longest Path, driving predecessor tracing, weird EV summary roll-ups(?)).

Both lists are still a lot shorter than the one about things which look like
they don't work or aren't there but are really the result of user
mis-understanding about CPM/MSP.

Trevor
----------------------------------------
 
J

Jan De Messemaeker

Hi,

Do you have MS speakers at the PMI that do understand Project Client?
I wasn't so lucky, the Belgian guy said never assign resources to tasks they
may inadvertently change duration, link summary tasks rather than normal
tasks etcetera..
He was a knowledgeable Server user, I admit, but he hated the fact that the
client "does all crazy things with your dates".

Greetings,
 
T

Trevor Rabey

Did you correct him, afterwards during drinks?
I am a member of PMI Sydney and recently attend meetings at PMI Western
Australia. I haven't met the resident MSP expert or MS rep/distributor yet .
Can't wait.
I would love to be able to see the code that does this glitch, and which
evades the testing.
How can everything else about linking and leveling work but this not work?
There must be an IF() THEN not working somewhere, or one missing.
Never in the history of software has the proportion of the number of people
(including the authors) who know what they are doing and how the methods and
tools work been so small compared to the number of people in the entire user
base (including the authors) than with MSP, and then this, which is a
genuine surprise even for the experienced.
There never stops being something to learn about it.

Trevor
 
J

Jan De Messemaeker

Hi Trevor,

I've done some more testing, even tried this one day at the time and behold,
at each pass the task is delayed 2 days.
It looks like the code passes two times on the spot where leveling delay is
upped.
And BTW, leveling is also very weak on FF relations.

Pity because 99% of the woes claimed on leveling are wrong, it is a nice
piece of function!

Greetings,
 
D

davegb

Trevor said:
Congratulations Andre.
There must be a big finder's fee to go with this.
I wish I had discovered a real bug.

Putting them back to:
T1 5d A
T2 5d B
T3 5d A 4SS
T4 5d B

If you add the 2FS link at T4, and then level, OK, T3 ES = 02/01
If you force T4 to Must Start On 02/01, and then level, OK, T3 ES = 02/01.
If you do either and then take them off and then level again it goes bad
again, T3 ES = 09/01.
So, any way that T4 gets forced to 02/01, except levelling, makes/allows the
4SS link work OK.(?)

This is a tiny glitch and rarely encountered in practice, but unnerving.
As well as a good argument for ensuring every Task has at least 1 FS
predecessor, and a strict minimum of all other types, which is good advice
anyway, it's a bug.
Is it a leveling bug or a linking bug?
The linking works ok if there is no leveling, so it must be a leveling bug,
but it only happens with this link.
If leveling is set to manual, and other calculation automatic, then leveling
can only happen when you push the button.
If then leveling does something else (mysterious), as well as "delay Tasks
to remove Resource over-allocation", then I will not be able to advise
students/clients etc that "Leveling is simple. Leveling delays Tasks to
remove Resource over-allocation, and nothing more", which is also very
common advice on this NG.

The levelling delay of T3 and T4 both stay at 7 Edays, even when T3 is
scheduled for ES = 1 week later than necessary!

You have to admit, this is disconcerting at least for anyone making a living
out of MSP, and erodes the faith of the faithful and members of the MSP fan
club who have to teach this stuff and defend MSP from the people who say it
is crap and P3 is better.
I must remember this one for next time the MSP spruiker is making the big
pitch and demo at the software show or the PMI chapter meeting. No, that
would be unnecessarily cruel.
Is there any chance MS is going to fess up on this;-) ?
Click to expand...

Surely you jest! :)
 
T

Trevor Rabey

Julie, I think you might be running the wrong example.
You show T2 and T3 with the leveling delay.
But T3 and T4 are the two which should get level delayed because T1 and T2 have the higher priority (520).
Try

T1 5d ResourceA
T2 5d ResourceB
T3 5d ResourceA 4SS
T4 5d ResourceB

Before Leveling:

Task, Leveling Delay, Priority, Duration, Start, Finish, Predecessors, Resources

Task 1 0ed 520 5d Mon 26/12/05 Fri 30/12/05 A
Task 2 0ed 520 5d Mon 26/12/05 Fri 30/12/05 B
Task 3 0ed 500 5d Mon 26/12/05 Fri 30/12/05 4SS A
Task 4 0ed 500 5d Mon 26/12/05 Fri 30/12/05 B

After Leveling:

Task, Leveling Delay, Priority, Duration, Start, Finish, Predecessors, Resources

Task 1 0ed 520 5d Mon 26/12/05 Fri 30/12/05 a
Task 2 0ed 520 5d Mon 26/12/05 Fri 30/12/05 b
Task 3 7ed 500 5d Mon 09/01/06 Fri 13/01/06 4SS a
Task 4 7ed 500 5d Mon 02/01/06 Fri 06/01/06 b

Task 3 shows only 7ed Leveling Delay yet has Start = 09/01/06, which is 14 ed from 26/12.
If we Level without the 4SS link, T3 and T4 both go to Start = 02/01, OK.
If we now put in the 4SS link T3 should not move because it is already scheduled to start as soon as the 4SS link would allow.
But it does move to Start = 09/01 and Leveling Delay does not change.
 
J

JulieS

Hi Trevor,

In Andy's original post, he wrote he was leveling using a Leveling Order of
"Standard, Priority".
When I level the original tasks as noted by Andy, using a leveling order of
"Standard" (as there is no Standard, Priority in my version of Project) I
get the results I noted in my first post: Task 2 and Task 3 are delayed.

When I level the same tasks using a leveling order of "Priority, Standard"
then I get the same results as you have noted, Task 3 start of 9 Jan 2006.
I agree, task 3 should not need to be delayed until 9 Jan 2006.

My apologies for adding to the confusion. I should have noted that I used
the leveling order of Standard.

Julie
Julie, I think you might be running the wrong example.
You show T2 and T3 with the leveling delay.
But T3 and T4 are the two which should get level delayed because T1 and T2
have the higher priority (520).
Try

T1 5d ResourceA
T2 5d ResourceB
T3 5d ResourceA 4SS
T4 5d ResourceB

Before Leveling:

Task, Leveling Delay, Priority, Duration, Start, Finish, Predecessors,
Resources

Task 1 0ed 520 5d Mon 26/12/05 Fri 30/12/05 A
Task 2 0ed 520 5d Mon 26/12/05 Fri 30/12/05 B
Task 3 0ed 500 5d Mon 26/12/05 Fri 30/12/05 4SS A
Task 4 0ed 500 5d Mon 26/12/05 Fri 30/12/05 B

After Leveling:

Task, Leveling Delay, Priority, Duration, Start, Finish, Predecessors,
Resources

Task 1 0ed 520 5d Mon 26/12/05 Fri 30/12/05 a
Task 2 0ed 520 5d Mon 26/12/05 Fri 30/12/05 b
Task 3 7ed 500 5d Mon 09/01/06 Fri 13/01/06 4SS a
Task 4 7ed 500 5d Mon 02/01/06 Fri 06/01/06 b

Task 3 shows only 7ed Leveling Delay yet has Start = 09/01/06, which is 14
ed from 26/12.
If we Level without the 4SS link, T3 and T4 both go to Start = 02/01, OK.
If we now put in the 4SS link T3 should not move because it is already
scheduled to start as soon as the 4SS link would allow.
But it does move to Start = 09/01 and Leveling Delay does not change.
 

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