INVOIC02 negative posting

Hi Everyone,

Am using INVOIC02 for EDI vendor posting. If the amounts are positive the posing key 40/31 is derived correctly; I need some help in posting -ve Invoice.

By just making the E1EDP26-Overall as -ve the posting key 50 is derived correctly however credit Memo entry is not getting derived while testing in foreground using we19.

OBCE has Document type KG for Credit Memo.

Do I need to fill any other segment in order to post a credit Memo.

Thanks,

Yogeeta