Streaming from iTunes to Apple TV 2

Hi,

I am unable to stream a movie I bought through the iTunes store to my Apple TV 2. It says "your Apple TV is not authorised to play this content" when I try from my iPad, and just displays an unknown error (406) message when I try from iTunes. It's all on the same account that I purchased the movie with, so why unauthorised? I have tried turning everything off then back on and am running all the latest software. I also appear not to be able to sync to the Apple TV as it's not appearing in iTunes anywhere.

Nobby