Dragon Age II - Achievements not Unlocking After Loading previous Save Game

I've reinstalled Dragon Age II and loaded the post campaign save game I've kept on my PC, but no achievements are unlocked.

When I've played the first time, I hadn't a connection, so I haven't syncronized with BSN my walkthrough.

There's any way to unlock the achievements, or I have to play DAII all over again with the data syncronization enabled?

Thanks in advance for the answers!