I'm trying to use an M Audio EXP to control the master volume in MainStage. I'm plugging it into the silver (the one closest to the inside) port. When I move the pedal up and down, it is displaying the G H and I notes. In MainStage, the fader will erratically jump up and down. I'm kind of at a loss, and would really like to use the pedal. Any thoughts? Thanks guys.