It appears something is up with the codes GameStop and Amazon were giving out for Fable II pre-orders. The code was supposed to allow people to download a free copy of the stand alone Fable II Pub Games, but we've received numerous reports that the codes don't work. Reports of the code not working have also cropped up over on Xbox Live Director Larry Hryb's Major Nelson site. There's also a forum posting on Xbox.Com that lists more than 100 people not being able to use their code to download the game.
We've contacted Microsoft for comment and will update once they get back to us or find a solution to the problem
Update: Just heard back from Hryb: "If you received a download code from a pre-order for Fable II, I am being told that they codes should be working later today. Apologies for the delays."