Apple TV streaming vs syncing and not doing either

Question

I have an Apple TV and a MacPro with an iTunes Library on it. I went to get the ATV on the network and that was just fine. I can get on the internet and watch trailers and download and watch movies. But the iTunes Library won't either stream or sync. It certainly won't sync. It says [in preferences] that it is streaming. And when I check the ATV again ref. the shared libraries of music or photos or podcasts etc, it says "Loading XX Library" - and it's been doing that for about 10 minutes = and I'm right now just testing it with 7 photos and it's not going anywhere.
Network works, ATV can get on internet, it shows up in iTunes, the iTunes Library on the computer is properly named and listed as one of the 'computers' but it won't load to either sync or stream.

Answer 1

It's all about which set up you choose when you set up the library. When you click on the tv in itunes how many tabs do you see (as per the link). If it's only 2 you have set up a secondary library and a secondary library cannot sync.
If this is the case you need to delete (disconnect) on the tv (see the bottom pictures on my link), then you need to start again by 'connecting to itunes' (the top one in the list-where I've denoted 'add a primary library) you will need to go through the pass code thing again, but before you do, look in itunes preferences-tv, ensure that look for Apple tv's is selected and delete any tv's that are already in the list there.