Microphone Trouble Mac Mini

I am very new on Max OS X ... I'm hoping this is very obvious. I recently purchased an iMic to use with it, wanting to set up skype with it. The output sound works fine in terms of music, whether I use the internal speakers or the iMic.

When I connect a microphone to the iMic, whether I have it set to line-in or microphone, if I speak into the microphone on the system preferences->Sound->Input page, the level goes up and down as if it can hear me, but I hear no sound coming from the speakers.

I downloaded Audacity, which I have used on Windows, but when I put it on record and talk into the microphone, it just flat-lines...when I look into preferences->devices, I don't see any indication that it even recognizes that the iMic device even exists.

So, it's like the microphone sort of works (at least on the level), but yet it doesn't. I'm hoping this is some really simple obvious thing. Like, in Windows, I'd have this figured out in no time flat, but on the Mac, nothing is quite so obvious, if you know what I mean.

On googling, I can find stuff about microphone troubles, but haven't found anything quite like what I am looking at. Thanks in advance for responding to this

I recently had USB mic input/no sound problems with a BLUE Snowball mic. There were a couple of combinations of problems, i.e. the computer couldn't "see" the mic or it would see the mic but I couldn't hear the sound, but I had levels on the meters (in System Preferences). It turned out that the problem was that I was using a USB hub (powered)...the same one I use for media cards and flash devices. For the cards and drives, it worked fine. So I didn't suspect it to be the problem with the mic. Once I plugged the mic directly into a USB port on the computer, everything worked fine and continues to do so.

Thanks for the insight. I will check that out...