Most codes are region specific and must match your Battle.net account region before you can claim them. Regions-specific codes cannot be transferred from one region to another. If you're having trouble claiming a code, make sure the code was entered correctly on the Code Redemption page. If the issue persists, contact Customer Support help.
If you're having trouble claiming a code from a card purchased at a retail location, make sure it was activated at the point of sale.
Note: Item or pet codes distributed prior to BlizzCon 2009 and all World of Warcraft Trading Card Game item codes must be redeemed through the World of Warcraft Promotion Code Retrieval page.