I need help with JAM for my electro-acoustic guitar

I got an amazing electro-acoustic tanglewood yesterday for Christmas along with the JAM device thingy. I've plugged it into my mac (which runs iLife '11 and Mountain Lion). When I open Garageband, the light turns green (from blue). I've gone to preferences and changed the audio input to JAM and turned the monotoring on. When I play, the green light 'flickers' at each note which I assume means it is picking up that note but nothing appears on the screen when I record or even when I'm just trying to test out the sound.

😕 Confused