Posted this in realms too because I'm not sure where to put it.
I just bought a realm and it told me the "To initialize your uninitialized Realm[/b] start Minecraft as you normally would and select Minecraft Realms from the first in-game screen. We will guide you from there." message in a yellow box on the realms tab. When I follow the directions given, it doesn't show up and send me back to "buy a realm". Screenshots are below to show what i mean.