hi gonzo
i am experiencing the same problem since a couple of weeks. i was on the phone with apple support hotline for 6 hours today, but they weren't able to help me. i had a date at the apple store genius bar as well, but they couldn't help me either.
but: the guy at the apple store told me, he had the exact same problem with his private iphone and remote app since about 2 weeks. it worked perfectly fine before. he said to me that the problem might be the remote app.
we restored the iphone now, and lost another 2 hours (of my precious vacation time). then, for a few seconds i could see the iphone in the left sidebar of itunes, was able to enter the code, but then itunes said the code was wrong. after that the iphone icon disappeared and again everything is as before - simply NOT WORKING.
and: i tried it with the mac pro, with the macbook pro, with my iphone 5 and the old iphone 3gs. nothing was working.
we tried so many things during 6 hours, nothing worked. i had to send my system infos to with a little program the supporter sent me, and he will send this to the engineers now. i hope, i will get more info tomorrow regarding this issue. anyway, all these problems are occurring only since itunes version 11. before, everything worked fine, and itunes 11 is just a huge pile of cr@p. no multiple windows, no genius side bar, no cover flow, all the functions are hidden, so you don't find anything. it's really a p.i.t.a.
i already sent at least 10 feedbacks to apple directly. and so did probably thousands of other users. but they don't react. nothing happens. it's just this crippled itunes version and nothing works anymore.
any hint what i could try?
my systems: mac pro, os x 10.7.5; macbook pro, os x 10.7.5; iphone 3 gs, iOS 6.1.3; iphone 5, iOS 6.1.3
on both computers itunes 11.0.4.
so, everything is up-to-date. my wifi lan is working perfectly well, everything else is working. only remote app is not working. 😟