authentication key not waorking

[Lastblow]

this is what i get every time i try. The authentication key you entered cannot be claimed. Please check the key and try again. Alternatively, you can enter this key for a different region by changing the leading part of the www.battle.net URL (ex. “eu.battle.net”) in your web browser, or for a different Battle.net account. help?

[Sunshine]

Try contacting Blizzard.

[alexdefino]

Is your authentication for US? find the right place to enter it. Maybe you wanna have a US account, but your code is for EU, that may cause this situation.