Not getting error or warning massage for duplicate MIRO Credit memo
i have checked standard massage "M8 108 Check if invoice already entered under accounting doc. no."M8108 (if accounting documents are found).i have enter the message M8108 in table T100S using transaction
SM30 and then set it as an error via OMRM.then also not getting any massage or error.
Please active check Double invoice in the Vendor master and change standard message to information or warrning.