Why is it that Summary Task Duration does not equal List of tasks?

[Don V]

how can I get my Summary Task Duration to Equal the list of Tasks

Example
Test Summary task 8 days
Test 1 8 Days
Test 2 1 Day

How can I get the summary task to equal 9 days?
what am I doing wrong?
I have read many links but none of that explains how to make this happen
thanks

 

[JackD]

The "duration" is the number of days between the start of the task and the
end of the task.
If your two subtasks overlap then the summary will be equal to the longest
of the two. If they are in sequence then it will be equal to the total, if
they have gap it may be much longer.

Work is based on hours of work and should sum up correctly.

-Jack Dahlgren
http://zo-d.com/blog/