Did you beat any of the game with cheats enabled? Cheats disable achievements from unlocking. It might be you beat a level with cheats active? I know they disqualify you from the intel achievements not sure if they do the same for the rest of the achievements, I imagine they would.

I want to get a JRPG for the 360, which should I get?

Tales of Vesperia

Lost Odyssey

Eternal Sonata

-Foobar-

I'm looking for a game where you play the Necromancer, much like Diablo 2. I know Fable II has the raise Dead spell. I don't really see that in Oblivion, correct me if I'm wrong but is necromancy available in Oblivion? I know they have Vampires, but. I want a game where you have minions and you're in charge essentially but you can upgrade your minions and wreak havoc etc. I prefer 360 platform.