Arduinoboy MIDI. Optocoupler issue (I think)

Hello guys!

I've been struggling all afternoon with a problem concerning my Arduinoboy project.
The problem seems to be in the midi in section of my circuit, since I don't seem te receive any midi.

I'm using a 6N137, 6N139 or MCT6 optocoupler instead of a 6N138, but that should work too right?

Here is a photo of my circuit:

And here the schematic which should be applied:

I hope you guys can see what's wrong, because I just lost sight of it, haha.

Thank! :slight_smile:

The 6N138 and 6N139 have Darlington amplifiers and should be interchangeable. Not so the 6N137.
I couldn't find data sheets, check the pinout yourself.