Third party billing partials for zero

After an enhancement upgrade and addition to IS-OIL to SAP, we are generating zero dollars for our billing document for third party sales orders.

The only time this is occurring is when we are generating partial bills.

For example:

Sales order qty 10

PO created for qty 10

GR created for 4

Program executes creates a bill for the full amount for four.

Then few days later GR created for 3

Program executes creates a bill for zero for a quantity of three.

Then a few days later GR created for 3

Program executes creates a bill for the full amount for three.