To even be allowed to do this puzzle you must buy Eine Ritterrundfahrt from Omi in Tempest Bay.(12758, 11713) The book costs 5 Magischer Schafsmist which you get for turning in 10 sheep for the quest Verirrte Lämmer. You can do this 5 times in one day by abandoning the quest before turning it in. You also need to complete the artifact set by the same name. A Knight's Tour