Can't open the Lunaris Temple

I searched the forums and found nothing related, so here is my problem:

I have the final Act 3 Quest for killing Piety (Piety's Pets) but I can't open the door to the temple. I click on the door and it only says "The door is locked". I have nothing to open the door. This is my second char to go for her on normal, with the first everything went fine.Did I accidently sell the item to open the door? Is it possible to sell quest items? If yes, what can I do?

The door you are trying to open is not the Lunaris temple.
Find another door in the area with the name Lunaris Temple, that will open.

Oh, you're right, thanks ... :)