How to add custom buttons to MB52?

Question

I created a custom transaction code ZMB52 by copying the standard SAP transaction code MB52. In the program, I'm trying to add two custom push buttons to the ALV toolbar, but the buttons are not appearing when the ALV is displayed.

Here’s what I have done so far:

1. Edit GUI Status 'STANDARD' in SAP GUI

   

   I attempted to add new buttons or delete existing ones in the GUI Status.

   However, when I execute the program, the changes (additions or deletions) have no effect on the ALV toolbar.

   

2. I searched through the program for any specific code or form related to configuring this status, but the only relevant line I found was this:

   

Despite editing the PF-STATUS or trying other approaches, I haven’t been able to make the new buttons appear.

Has anyone encountered a similar issue or knows how to resolve this?

Any guidance would be greatly appreciated as I’ve been stuck on this for a whole day.

Thank you!

EDIT: I realize something:

• First, in the mb52 standard program, the GUI Status STANDARD wasn't called from any screen (the toolbar displayed is one set by default by SAP), that's why I try to change add or delete also not affect to the tool bar.
• Second: the GUI Status must have to call by FM 'reuse_alv_.....' ==> this one in some standard program SAP they are using not a normal 'reuse_alv_grid_display', they are using 'alv_detail_func' ==> this one also has to debug to figure out.