Diagnosis
You tried to reverse billing of mass simulation index &v1& forinstallation &v2&. The two simulation documents &v3& and &v4& werefound for this index. These simulation documents have the same billingperiod.
Possible cause of the problem:
You billed the mass simulation index
You then deleted the mass simulation index without deleting thesimulation document
You generated the mass simulation index again with identification &v1&and billed it again.
You cannot reverse the billing of the mass simulation index.