same thing here, I've had the game for over a week and have not been able to link my account. as far as I can tell it's a server problem. The same thing happened on GH3 when it first came out but that was due to the severs getting dumped on and not being able to handle the load, but this is different this game has been out for a while so that should not be an issue. I have talked to a couple of people who have had the game for a while and they have not been able to update their scores so it must be a system wide thing for PS3 users.
I'll tell you with the guitar compatibility issues and now this I'm beginning to think Harmonix doesn't give a crap about PS3 owners.