Diagnosis
During outline contract billing, discounts are determined based on totalconsumption. These discounts are created in IS-U as flat-rate scaleprices using the master data generator.
During billing, a price amount with a pricing quantity is determined inthe variant COMPUT50. The result is updated as a factor.
The factor is used as a discount factor with variant LUMSUM02 ina subsequent step.

Procedure
Check your master data template.