Problem with macro in MDI mode

Hello,

I'm trying to implement a macro for setting the tool length with a probe on the table. The subroutine i wrote is working and does what i want it to. Now I want to embed it as a macro in Gmoccapy so I have fast access to it in the MDI tab.

I followed the steps listed in the documentation and added a macros folder in my config directory. I added my .ngc file here. The ngc file itself has the blocks at the start and end
O<my_routine> sub

O<my_routine> endsub
M2

I added the necessary lines in the ini file as well.

Now when I press the macro button at the bottom left in the MDI tab (the button has the correct subroutine name on it) I just get the error "file not open" and my subroutine does not execute.
When I open the subroutine file in the Automatic tab, then go back to MDI I can run the macro no problem, but as soon as I load another program the subroutine button does not work.

I hope someone can help me as I'm pretty sure it's just some oversight on my part.