After extensive testing, I was unable to get iTunes Music Store to work - at all. Complete fail. The best I could achieve was to get the music player to work.
Frustrated, I went looking for a decent alternative. Enter Google Music...
It might be worth a look-see because it'll work no matter what device or OS you use, because it's web-based.
Being web-based, it offers way better features, like the choice of multiple downloads of music purchased and/or streaming it from anywhere from the cloud. You can also upload your music to the cloud too - upto 20,000 tracks for free. The Store music is high-quality (320kbps) mp3, which is playable on many players available today.
Sorry, not meaning it to sound like an advert, but it's really that good!