I have the Alesis Multimix 8 connected to macbook pro via usb. When I plugged it in, the mac recognized it and made the input "usb audio CODEC" in Garageband. I also went into mac system pref. and chose the usb audio codec input. I'm getting sound from the headphones plugged into the alesis, so the instrument is working, but garageband is not picking up a signal. Record is enabled on the track. Input source is usb audio codec on track info. but nothing. Do I need a special driver or something? Any input appreciated. Long time musician, newbie to home recording!