You must own both the Dark Below and House of Wolves, on the same account as you are purchasing The Taken King digital download version. Having access to another account's copy via digital rights management, is not sufficient. If you do own both on the same account you are attempting to make the purchase, try restoring licenses: https://www.bungie.net/en/Help/Article/12181 Next, try "purchasing" the standalone year 1 expansions from the marketplace. If you own them on your account, they should be listed as zero cost (verify this before proceeding). If all this fails, and you do own both year 1 expansions on your account, contact Microsoft for assistance. They own the store and the licenses attached to your account, so if there is a problem with either they will have to resolve it on their end.