SAP Message AH667 - Not possible to determine alloc. date for meter reading unit &1 date &2

Diagnosis
Internal error:
During analysis of the schedule records, an error has occurred in thefunction module ISU_ALLOCATION_DATE_LOCATE when calling in LEA00F05.The call parameters always require a result, even if scheduling is notmaintained completely. This needs to be corrected.

System Response
Processing is canceled

Procedure
Please contact SAP