I'm want to record some of my roommates' music on my PowerBook, so I went out and bought an external mic. It has a standard 1/4" plug, and a 1/8" adapter to plug into the line-in on my PowerBook. Problem is that when I push the record button in GarageBand with everything hooked up, it doesn't record anything It seems like it's recording something, but when I click to stop the recording, the track just disappears. Please help!!!