There's multiple ghosts on the entire map. I don't want to give away any spoilers, but just make sure you talk to all the ghosts and listen to what they have to say. It's similar to an Indian Jones and the Fate of Atlantis puzzle.
If you are still stumped, you should try clicking all the options when you look to open the talking door.
If you are still stuck, you can PM me if you don't mind spoilers.
Thank you, as it turned out, I have missed one chamber somehow. Anyway, there is no bug here. Carry on