I've never used the Radio feature, but lately there's been a weird glitch screwing up the Remote app related to radio. When the Remote App connects to iTunes, for some bizarre reason, iTunes tries to refresh its list of hundreds of radio stations, which you can observe in the iTunes message area at the top of the window; there will be a line "Contacting tuning service" and below it another line, "Refreshing <genre>". Lately it's been failing partway through, putting up an error box, "An error occurred while contacting the radio tuning service. Check your Internet connection, or try again later". This error box must be dismissed in iTunes, and until you dismiss it, some of the Remote app controls won't work right. I use Hippo Remote to start iTunes from a distance, and it kind of defeats the purpose of remote control if I have to go to my computer to deal with this stupid iTunes error concerning a feature I don't use, that cannot be disabled.
Anyway, the good news here is that the radio list refresh has been completing successfully the last couple of days. It takes iTunes about 5 seconds to do it. I'd agree with Damian that it's an Apple problem, as nothing has changed on my end.