Yes, I am running latest version of iTunes. One possible reason could be that I did a clean install of Yosemite, Not sure if that might be causing problems. My iTunes account is the same and I have reset Apple TV. To all intents and purposes, everything is in order.
Have restarted Apple TV several times, updated software and checked that home sharing is on in iTunes. It simply won't acknowlege iTunes since upgrading to Yosemite. I love. Challenge but this is so frustrating considering everything worked perfectly before upgrading.
Long shot, but there is a bug in Yosemite (and mavericks and several generations back) where if your Mac goes to sleep and the network loses connections, when it wakes up and reconnects the name of the Mac will become "whatever (#)" where whatever is the original name and the number increments up from 2 to infinity, I guess. That's why nickyr had to delete the (11) from his machine. There is no fix. But this article discusses some possible approaches. What I did was to go into System Preferences/Energy Saver and set the Computer Sleep slider all the way to the right at "Never." That way the CPU never shuts off and you never lose the WiFi connection, so the renaming doesn't happen. You can let the display sleep have the screen go black, just leave the CPU ticking over. It seems to be working for me.
I am somewhat embarrassed, but I have just fixed this problem.I have been trying to set up Home Sharing through iTunes preferences. There is a tick box there so I thought that was the only option. However, I found there is a Home Sharing link the dropdown menu. I clicked and hey presto I am back online. Thanks for helping and sharing my frustration.