My mute button does not work - if I slide it, the mute icon appears, but the sound goes right on playing. This so with all the apps I've tried it with. Yes, it's the latest OS, 4.2.1 Funny thing is that I'm pretty sure that it did work when I first got the iPad about ten days ago. But it doesn't now. It's no biggie, since the volume zooms right down if you hold it, but it should work. Any suggestions as to why this should occur? There's nothing in the settings that I can find. Or is the button just dead, and I should contact Apple? Thanks!