iPhone No volume control shows up on specific phone when using MPMoviePlayerController

We've written an app that uses the MPMoviePlayerController to play movies streamed from a server. It works fine on a bunch of devices we own (2 iPads, 3 iPhones) and a few others at our customer site but for one particular Japanese fellow, he gets no soun开发者_JAVA技巧d and no volume control?

Any suggestions?

PS I did ask him to reboot his phone and he has the vibrate switch off

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ok it does pay to ask silly questions a second time. He did have vibrate switch on. Now the question is why YouTube app doesn't remove the volume controls when that happens and our app does but I just need to research that now.