I can't get it to work. I have it turned on on my macbook air, and on my iMac at home. Have file and screen sharing on. The imac shows up in my list of devices in the Finder window on my Macbook Air, but when I click on it, it just says 'connection failed'. I read up on it a bit, but haven't found any info on what could be wrong/what I need to do? thanks for any help!!!