External Firewire Audio Input does not record

I am using a new Alesis Multimix8 Firewire mixer, connected to my iMac, using Logic Pro 9. If I use the microphone hooked up to the mixer, and I play something, I see the sound meter move on the mixer, so it is getting signal. I also see the sound meter move on the iMac internal general settings, so the signal is getting into the computer. However, I cannot seem to get Logic Pro 9 (or Garageband) to record from this input. I may have shut off the internal iMac microphone, at some point, also, to see if this is the problem. I have over 20 years Windows experience, only started Mac back in June. I am also new to Logic Pro 9 (yesterday I installed it). However, this particular problem seems to be consistent with several other recording packages I am using on this iMac (Cubase & Garageband).

So, the signal makes it into the computer, but not into the software. Any assistance you can give would be greatly appreciated!!!