Scheduling in 8.00.810C

We are scheduling all of our jobs forward and finite through Global
Finite Scheduling.
We are also using the Advanced Planning and Scheudling module.
We have all of our 2376 purchased parts constrained.
We are finding problems with how the system is allocating parts.
The parts are not being allocated in the correct order by the ship
date on the sales order.
I have noticed that sometimes the on hand quantity and PO due date is
ignored and it is scheduling the jobs off the lead time for the part.
Epicor thinks that it is because we are constaining all of our
Is anyone else seeing this same or similar issue?
Thank you in advance,