Trading partner incorrectly getting populated in TI Document.

We are having issue with population of Trading partner field in TI document for certain Transaction types.

The issue is specific to Company code - 1012( Payment order between 1012-1020), in all other cases ( payment order between any other company code and 1020) is working all right.

The Trading partner that is getting updated is incorrect.

Step- Post payment order.

After posting of Payment order the End of day sequence of steps were executed, the following are the sequence of steps taken : -

T ocde - F9B1 F9B1 Posting Cutoff - Payment transactions. Account Balancing, T code - F991 F991 Mass Acct balancing (Interest / Charge Calculation). Account Clousre, T Code - F9KD F9KD Report : Account Closure. Closing Date, T Code - F9L4 F9L4 Date of Balancing Posting Entry. Bank Statements - F9N1 F9N1 Start Bank Statements. Balance sheet Prep, Tcode F9HL F9HL Balance sheet preperation Bank Customer Accounts - FI General Ledger. FI Transfer, T Code F9HI F9HI Transfer Bank Current Accounts - FI General Ledger. Bank Statement posting, T code FEBP FEBP Post Internal Bank Statements

On executing the T. Code - FEBP the TI documents got posted with incorrect Trading partner.

Similar document is posted in Company code 1020 with In correct Trading partner.

The Trading partner is populated based on Substitution rule and where ever the XRFF3 (Reference key3) key is populated , trading partner is posted correctly based on substitution rule. Where ever the XREF3 key is not populated the Trading partner fails to update correctly.

Based on initial analysis it seems that issue is owing to XREF3 field not getting populated in case of document posted in 1020.

It will be big help if you guys can throw some light and help solve this issue.