Forward Scheduling Problems

We are in the process of implementing Vantage 8.03.305H on Progress
OpenEdge, and we are struggling to make finite forward scheduling
work as I anticipated it would. Here is a simplified scenario that
explains what we are trying to do; perhaps you smart people out there
can help.

Let's say our Bill of Material looks like this...
... where D is a purchased item, and C, B, and A are manufactured and
make-to-stock. "A" is what we sell. "C" is a large recipe of
material that cooks in a furnace for 12 hours, and is then used to
make "B"s (and other sub-assemblies). "B"s are then assembled into
the sellable product.

The furnace runs of "C" drive our business. Based on these runs, we
want to forward finite schedule our factory, and provide commitment
dates to our customers. All components are coded as "critical", so
the forward scheduler can drive the start date for B when C is
finished, and the start date for A when B is finished.

Our Epicor implementation consultant has tried everything we can
think of, and can't get this to work. The schedules for B and A seem
completely unrelated to the Furnace run ("C"). We can't seem to
forward schedule from the furnace to get the ship date of the order.

Is anyone doing something similar? Any ideas?