I'm trying to write a programm on Teensy 3.1

- I got my Teensy connected in MIDI mode
- I got an other MIDI controler connected (in USB)
- I can interact with Softwares with the 2 devices

=> problem: it seems that the "usbMIDI.read()" fonction doesn't work because it always return "false".

And idea to debug and find the source of the problem ?