MIDI connection button problem

Hello,
I'm testing samplerbox with a pi3 and the latest img.
With usb connection all is working fine and I also mapped 4 button of my Impulse 61 to navigate the menu.
Once I added a MIDI port to the project (I had a different optocupler, a 6n136, so I changed the connection and used a different resistor as found elsewhere in different MIDI project) I still can play the notes but can't navigate the menu with the extra MIDI button of my keyboard.

Any suggestion?

Found the problem thanks to console output: when connected via USB my keyboard is identified as <Impulse 61>, when connected via MIDI is identified as <MIDISERIALPORT>, so I have to change the definition in the config.ini when I want to swap the connection type.