marco_c:
How are you connecting to your MIDI device?
This is the (rather convoluted) route I've tried with the Midi jacks...
Desktop with Windows 7 <=>
USB <=>
Arduino UNO <=>
Breadboard Wiring <=>
Midi Jack <=>
MIDI to USB cable (maybe it doesn't support Windows 7?) http://www.amazon.com/gp/product/B001HPL8B2/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1 <=>
Micro USB otg cable http://www.amazon.com/gp/product/B005GGBYJ4/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1 <=>
Nexus 7 <=>
Grand Piano pro version (supports Midi via USB) https://play.google.com/store/apps/details?id=com.als.grandpiano.free&hl=en
Leaving aside bugs I might have caused, does this seem like a route that should work? For the record, I've plugged a Midi keyboard into my Android before using a USB + otg cable and it worked just fine.