How to trigger SAPFM06P after adding or changing output type in message...

Hello Experts,

I want to debug my PO after adding or changing output types in the 'MESSAGE' button in ME22N. How do I do this?

For example, output type 'NEU' calls my custom program ZSAPFM06P(Copy of SAPFM06P) and custom sapscript form. It only

triggers when I click on the 'print preview' button.