Custom Message if Missing Agent Assignment for Release Approval process of Purchase Requisition

Hello,

I have used user exit M06B0001 for agent assignment for PR approval process. and this is working very fine.

I have used Z table to maintain Release Code and User ID entry for agent assignment.

What I required is custom message in ME51N and ME562N , if no agent is assigned through this user exit due to missing entry in Ztable.

pls help.

Thanks

Milind