Q: Apple Airplay not connecting to apple tv

Hi All,

I am having difficulty connecting itunes on my macbook pro to the Apple TV via airplay.  I have the airplay logo showing in the bottom RH corner of the screen but when I click on it, I get a connecting pop up box with a scrolling bar at the bottom but nothing else. After about 20 secs the box disappears and that's it.  The macbook pro connects happily to the apple TV via the 'computers'-'music' on the Apple TV without issue.  I can connect to the Apple TV using my iphone 4 via airplay without issue and I can use the iphone as a remote to control the macbook pro to select what music is played on the Apple TV.  The only thing that doesn't work iis trying to connect from itunes to Apple TV via Airplay : (

I am using mountain lion on the macbook pro, an Apple TV MD199B/A running 5.0.2 software which claims to be the latest version.

Any suggestions welcome : )

Many thanks,

Peter