Why won't MS Project allow relationship between two successive tas

[thebehm5]

I am taking a project management class and we are to enter in a diagram from
our text book. The problem occurs when we get to Task D and Task E.

Task E is predecessed by Task D in a start-start relationship with a lag
time of 2 days. Task E also has a finish-finish relationship with D with a
lag time of 2 days. When I enter this in, I get an error message.

Why won't MS-Project allow both a start-to-start and a
finish-to-finish relationship between two successive tasks?

Another quirk in this problem is that in MS-Project, Task F will not be
shown to have 12 days of start-slack. Task F, dependent on Task A in a
finish-start relationship, could start as early as day 5, after Task A is
completed, or as late as day 17, to make sure that the task is completed by
day 20.

Why does MS-Project believe that the Earliest Start Time of Task F is also
day 17? It should be day 5.

 

[Jack Dahlgren]

I am taking a project management class and we are to enter in a diagram
from
our text book. The problem occurs when we get to Task D and Task E.

Task E is predecessed by Task D in a start-start relationship with a lag
time of 2 days. Task E also has a finish-finish relationship with D with a
lag time of 2 days. When I enter this in, I get an error message.

Why won't MS-Project allow both a start-to-start and a
finish-to-finish relationship between two successive tasks?

Just the way it is I'm afraid. There are situations where the resulting
calculation would be indeterminate. One way to work around it is to place a
dummy milestone in between one of the relationships. For example try a 0 day
milestone between Task D start and task E start. Or put one at the end. That
should solve your problem.

Another quirk in this problem is that in MS-Project, Task F will not be
shown to have 12 days of start-slack. Task F, dependent on Task A in a
finish-start relationship, could start as early as day 5, after Task A is
completed, or as late as day 17, to make sure that the task is completed
by
day 20.

If you put a finish milestone on day 20 and make task F a predecessor to it,
it should show 12 days total slack

Why does MS-Project believe that the Earliest Start Time of Task F is also
day 17? It should be day 5.

Hard to tell without seeing how you modeled it.

-Jack Dahlgren

 

[thebehm5]

Thank you, Jack. That qanswers a few things. Let's see if I can show how it
is set up...
Task Duration Start Finish
Predecessors
A 5 days Mon 1/8/07 Fri 1/12/07
B 1 day Thu 1/11/07 Thu 1/11/07 1SS+3 days
C 2 days Thu 1/18/07 Fri 1/19/07 2FS+4 days
D 6 days Mon 1/22/07 Mon 1/29/07 1,3
E1 1 day Wed 1/24/07 Wed 1/24/07 4SS+2 days
E2 1 day Wed 1/31/07 Wed 1/31/07 5,4FF+2 days
F 3 days Wed 1/31/07 Fri 2/2/07 1,6FF+2 days

Task F only has predecessor TASK A, start-start, no lag time.
It also has Task E, Finish-finish, lag time of 2 days.

Can you tell me why the software shows no slack time, when is should show 12
days, and why it shows beginning on day 17 instead of an early start on day
#5??

Thanks,
Bill Behm

 

[Jack Dahlgren]

If you are talking about task F, then the FF+2d dependency with task E2
means it will not finish until two days after Jan 31. There is no slack and
it can't start any earlier and still finish 2 days later than E2. Delete
that dependency and you should see it shift back to where you are expecting
it.

-Jack