Customer Exits: Only show individual messages?

Hi all

we are using customer exits variables and do only want to show customer-specific error messages in the popup-window if there has been made a wrong selection.

We succeed in adding a message with fm RRMS_MESSAGE_HANDLING, but unfortunately, the "standard" message is still being displayed as well (e.g. "no value found for variable....").

So is there any way to only show the message created with RRMS_MESSAGE_HANDLING and to suppress the standard SAP messages?

Thanks a lot

Best regards

bivision