That's the main page of the Nostalrius bug tracker, but you have to register and confirm an account before you can start using it. Follow the instructions in
this thread for more information.
In the meantime, it's a known issue that sometimes a quest can't be turned in despite having all the required items in your bags. In that case, try the following: 1) delete your WDB folder under your WoW folder. This clears your game cache and downloads new information from the server, sometimes fixing quests the game thinks are incomplete. If that doesn't work, 2) abandon the quest and re-obtain it. Abandoning the quest should not destroy the items in your bags; instead it should force the game to rescan your inventory and mark the quest complete to turn in.