It gives you the error because an Origin code and a disc code are different and because its already been used to activate your cd copy. You'll need to contact live chat support and they'll usually be able to get you the origin version if you still have your cd key available. Unfortunately its an activation code not so much a cd key (like the old games were) so it'll only activate the game to your account. But again, EA should be able to help you through the process of activating it in Origin if you contact them in live chat.
