...but when I enter the code, I get the following message:

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Q u o t e:
This code is not valid. Please verify your code and re-enter.

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What's up with that?! This isn't fair, I was invited legitimately, yet I still can't even get that done right.

Yes, all keys should be working now. Sorry for the inconvenience. Now go show your friends how to play StarCraft 2!