Are you attempting to play on an expired 30 day trial/subscription?
Do you have the latest firmware update for your PS3?
Is Javascript turned on?
Have you tried reinstalling the game?
Have you redeemed the product voucher found on the back cover of your instruction manual?
Do you have your account registered in the Mog Station?

I'm just rattling possible snags, most of which you've probably already taken care of.