Gargeband Audio Tracks Glitching

So whenever I try recording something with the audio tracks feature (with any microphone) it won't work. When I play it back it's just clipping and it sounds like Garageband's trying to cut it out or something. I've watched several videos on changing the settings and all that but it still isn't working. It's the same issue with the guitar and bass recording feature. Also you can't see the waveforms it's just a straight line. It also happens when I import mp3 files where I can't see the waveforms and the audio's cutting out. Please help.