SAP Message BEA286 - Data inconsistency: item &1 of transaction &2 not in difference group

Diagnosis A difference calculation is to be created for billing due list itemSyst-msgv2/syst-msgv1. the system determined a group of billing duelist items for difference calculation. The billing due list items to bebilled could not be found in this group. System Response The billing due list item cannot be billed. Procedure for System Administration The cause for this may be a program error or data inconsistency.