MPMoviePlayerController Streaming Video won't play Audio

I'm s开发者_运维问答treaming video to my app with MPMoviePlayerController, works great in Simulator and my device, but one of my beta testers devices won't play the audio. Audio controls won't appear, and instead, show the following image:

Any idea what is going on? Thanks in advance!!

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The beta testers phone was on vibrate... dummy.