Missing Texture Help

Well, I'm doing work right on my Heretic level. I'm building a small village with a church/cathedral/what have you near the middle. I put a door to separate the outside from the inside. The problem is this: the walls near the door display HOM, yet when I look in Deepsea, there are no missing textures. I've tried to figure out what's causing this, to no avail. Some help would be appreciated.

Did you check the sector references?