Garageband problem or hardware problem?

Forgot to mention: Garageband does not register the drum machine through direct input to the computer either. I know the input selection in Garageband and System Preferences.

Are you trying to MIDI the drum machine to the computer, or just capture the audio output from its line out?

I'm not too familiar with garage band, but it sounds like a routing issue in the mixer. At bare minimum, you should be able to unplug your guitar from the mixer and plug in your beat box into the same port. Then it's either a) sound enters garage band, indicating a routing problem (see alesis manual) or b) no sound, indicating the box isn't pumping sound. either way, if you can get guitar, the problem isn't garageband or mac os x, it's in the alesis. check your busses and aux sends. (if available)

my guess: emptyinside provided a good start. but if i remember correctly, the alesis is an 8 channel firewire interface . So the reason you're not hearing anything in GB is because you only have a track with inputs 1-2 enabled in GB, and you need to make another one to account for inputs 3-4 or whatever inputs you're using on the Alesis. Such is the nature of multitrack recording. I'm guessing the reason you hear guitar and mic is because those are plugged into inputs 1 and 2 on the mixer, and that's what GB is choosing for the default inputs. Ideally you would have GB set up as Track 1: (mono) Vocals, Recording input 1 Track 2: (mono) Guitar, Recording input 2 Track 3: (stereo) Drum machine, Recording inputs 5-6 stereo (use 5-6 because, on the alesis and mackies, the first 4 are reserved for mono and the rest are stereo pair channels) p.s. eustacescrubb: midi is not a verb :)

Señor Pantalones, tell that to practically every music tech geek I know.