SAP Message >3133 - Specify a business partner or a contract account

Procedure
To be able to continue processing, you must specify which line itemsfor which business partners and/or contract account are to beprocessed.
If you enter a business partner only, the system processes all thecontract accounts for this business partner. If you enter a contractaccount, the system processes the line items for this account only andattempts to determine the correct business partner internally.