SAP Message >W050 - Not possible to derive account assignment REACC

Diagnosis
The cash flow analysis is active. As a result, each item of an FI-CAdocument must contain the account assignment REACC.

System Response
The system rejects the posting.

Procedure
The system automatically determines the assignment for the G/L items. Toalso set the account assignment in business partner items, the systemattempts to assign G/L items to business partner items.
If this standard logic (module FKK_SAMPLE_0066) is not sufficient foryour needs, then define event 0066.