I sometimes don't get sound from my Apple TV (beginning of 2013).

I connect the Apple TV with my Reciver with a HDMI cable.

I get sound: When I move in menus, When I watch movies from iTunes store and when I use Airplay with only sound (spotify).

I don't get sound: In Netflix app(Apple TV) and YouTube app (Apple TV), Airplay with video and sound content (like YouTube app (iPhone), Tv play apps (SVT and TV3))

The sounds have workt recently, since that I havn't change any hardware.