This may be a dumb question, but you're selecting AUX, right? If you are, then check to see if the screen on your mini has "scion" on it. If it does, then it's recognizing your ipod and the problem is elsewhere.
I have a 20gb color ipod that works fine. My girlfriend's 6gb mini works fine too.
I have a 20gb color ipod that works fine. My girlfriend's 6gb mini works fine too.