ISU Assess Workflow is doing full Reversal instead of Adjustment Reversal.

Hello,

I have Implemented the the standard ISU Workflow WS WS20500105, which internally uses: UtilBillingDocAuto.AdjReverseTab (BILLDOCAUT), but instead of Adjustment reversal it is doing a full reversal. can some one help as to which FM i need to use for Adjustment reversal.

Regards,

Jib