This only works if your fuction keys are set to hardware by default, and not software. Meaning, if you have a portable keyboard setup like a macbook/macbook pro/imac aluminum bluetooth keyboard, and you have to hit the fn key with F10, F11, and F12 to do your volume/muting-unmuting, then it won't work. Trust me. I'm on 10.7.4, Lion, and I just tested it. This seems to be the case. Chris.