Okay so I'm setting up an Apple TV and having issues with the audio. I've got it hooked up via HDMI and when I'm scrolling around the menu I can hear the little clicks of the menu so I know the audio is working. Then when I run iTunes I can have the audio play out of the TV. However the only time I cannot get the audio out of the TV if I'm mirroring. I can see my desktop and the visual part of the mirroring works okay, however no sound from the TV. Issue is I can go to System Preferences and chose Audio Output, I can see Apple TV it just won't let me select it. When I click Apple TV, it deselects?! Very frustrating, any help would be great!