Thanks All!
It has worked.. This was Agency Business.
I activated the "Multiple Issuing" for the relevant O/P message type. Also, we had a custom routine developed and there was a logic to email Credit claims processed using T-code: WLFF only. It ignored sending email to vendors, if the credit claim was processed using T-code: WLFG.
Now, we changed the program to include if any credit claim was re processed using T-code: WLN4 too and this has worked.
I thought it might help someone in need by explaining exactly how I resolved this thread.
Thanks & Regards,
Shilpa