Can't receive FaceTime calls on Mac

I can't make or receive Facetime calls on my Mac. It looks like it tries to answer but then gets rejected. When I tested it w/ my iphone it said that the caller was busy (when nothing was going on on my mac). Does this happen to anyone else and is there a fix for it?

And before someone posts it, I've already gone thru the basic troubleshooting instructions so just dont send it please...