#4 - April 14, 2010, 8:55 p.m.
There should be two separate authentication keys within your Battle Chest, Deadsquiggle; one for the World of Warcraft, and one for the Burning Crusades. It appears that you have registered the World of Warcraft key, but have not yet added the Burning Crusades key.
You should be able to register the Burning Crusades authentication key with your existing World of Warcraft account through the account management page (
http://us.battle.net/account/). However, please let me know if you need any additional instructions or assistance.