Stuck at level 90? One or several things might be happening:
You must have at least 280 AA to advance in Adventuring. The AA limit was hotly debated. What it came down to was this:
[T]he bar for earning XP in 90 is going to be 280, because you have your heroic endlines at that point (and I hate large primes so 277 wasn’t going to work). The requirement exists so we (the developers) and you (the players) have a little more information about what a level 91+ player is. Right now if you form a pick up group, you really don’t have an idea whether your tank has 65 AAs or 317 AAs. The same goes for us, content for a level 90 with few AAs is pretty different than content for a level 90 with a whole lot of them.