Comment by mikeash

I think Apple's problem with this stuff is that they want it to be so seamless that they refuse to acknowledge the possibility of failure. If you're lucky they'll tell you that something went wrong, but they almost never say what. In many cases they just swallow the error silently. I run into this with AirPlay a lot. When it works, it's easy, but when it fails it's a total mystery as to why. Fixing it involves either retrying until it works, or rebooting whatever is handy in the hope that you'll stumble across whatever's responsible.