Inventory Maint

We are using 4.0, but we have a problem that we did not encounter in 3.0.
In our warehouse that we have created for perishable tooling, even tho we
have each Part assigned a primary warehouse and a primary bin in the
Part Master File every time the qty on hand gets to -0- we have to re-assign
that part a location. If any one else has had this problem or if you can
a solution it would be greatly appreciated.

Thanks, Tammy