Before you hit the Record button, did you Target that particular mono Track?
Yes. The procedure I went through was the following.
1) Add Mono Track (Audio 3)
2) Click on Mic Icon in Audio 3, in the Audio Mixer.
3) Click on Record Button. Watch it flash.
4) Press the space bar to record.
Have you tried the mic in another program to make sure it is still working ?
You didn't read my first post. Yes, it works in Soundbooth and Garageband.