Error when running app

Hi, I just downloaded and installed BitTorrent and when going into the folder and running the WoW app I get a Error#121. It says DBFilesClientBattlemasterList.dbc has wrong number of columns. (found 31, expected 32). What did I do wrong? how do I fix it?

Close the game, then right click the torrent in the torrent list, and click verify or check data or whatever, then resume the download.