Apple TV2 won't play tv show

Hi,

I have just down loaded a tv show from iTunes and although it plays on my mac mini and mac book pro it refuse to play via th apple tv2 it says I need to autorize my computer which it already is or else it wouldn't play. I have bought many items from iTunes and this is the first problem I have had but I don't want to buy anything else unless I can resolve this issue, any ideas.

Thanks