Calculated date not an option for Gantt Chart

[Steve_Blane]

Hi everyone,
I’m new to AT and especially the Gantt view - so if this is already answered please point me in the right direction (I looked and couldn’t find it).
I’ve got my tasks set up. If I push my dates out, all of the successors push out just fine (e.g., if task A was ending Feb 1 and I change to Feb 5, Task B pushes out to Feb 5). When I shorten a duration, the successors stay in the same place (e.g., If I move Task A to end Feb 3, Task B stays at Feb 5).

This is pretty critical for us. Any suggestions?
Thanks
S