I'm in the process of replacing 11interior doors in my house. The new doors are solid pre hung doors. I've replaced eight so far. Two of them Creek terribly when open and closed. I've taken them out and reinstalled them each once. I've also greased the hinges and tried swapping out the hinges on one of them. Both doors appear to be perfectly level and plum. But they creak like they should be in a horror movie.

What am I missing? The other six doors that I've installed are perfectly quiet.