Please call AppleCare Hotline at 1-800-803-638, tell them you have this issue. Sometimes their database is a bit slow, or you have a very odd serial number that even AppleCare agents themselves got confused....

I tried that before, and my serial number contains numbers for the first 6 characters and alphabets for the last 5, instead of the conventional fixed alphanumerics. It never verified upon ACPP registration until a call to the hotline....