Message with type E not stopping execution in BADI and EXIT

Hello,

In my requirement, I want to show an error message and stop execution if certain criteria is met.

This is related to ME28 and ME29N. I would like to restrict the release cancellation activity for certain users.

So for this ,I tried to use exit - EXIT_SAPLEBND_002 and BADI - ME_PROCESS_PO_CUST.

At the climax, I wrote MESSAGE with TYPE as E. When that criteria was met, it showed error message but eventually processed the further execution which I want to restrict. Execution did not stop at MESSAGE TYPE E. I write STOP just after MESSAGE, however it was not processed.

I dont know how to stop the further execution. Any help would be appreciated.

Thanks