applecare problem

so i just bought my macbook pro from a local reseller today. got the latest model (released late 2013) from them for just over $2000 SGD. Now after checking my AppleCare coverage plan, I want to extend warranty by 2 years. I bought the AppleCare protection plan for Macbook pro and tried to register it online but failed with the following message :

We're sorry, but the registration number does not match the product or agreement type you have selected. Please check your agreement type or serial number and re-enter the information. If the information is correct, you may need to contact us.

Can anybody help me? I am pretty sure I keyed in the correct serial numbers.

Thanks in advance!

- J