Diagnosis
An internal error has occurred.

System Response
Processing is canceled.

Procedure
INCLUDE ISU_SAP OBJECT DOKU ID TX
Provide the following error message:
Inconsistency: The INTOPBEL field is set for the specified billingdocument. This indicates a reversal of the invoicing documentcorresponding to the billing document. The document number of thisinvoicing document should be in the OPBEL field, but it is not. Thissuggests an inconsistency in the invoicing reversal.