Arduino Midi Questions

Hello All.. I need help please !!!

Ok i got another Arduino Mega.. uploaded the Sketch (which didnt work on the old Arduino Mega) it did work on the Arduin 2009..
The Problem still is: The Arduino Mega doesnt receive Midi IN Signals.. but the Arduino 2009 does with the same sketch, how is that possible ? I am losing my mind..
Please help me out.. i dont get it..