Duct Tape

I have the linedefs facing the appropriate way and the texture is on the correct side of the door.

I'm using Doom Builder and I'm making a map in ZDoom (Doom in Hexen) format. I've made a door and it works, but instead of showing the texture I placed for it, it just shows an imprint of my screen until I open it. For example, if I'm looking at it and I move, my gun leaves trails. It's a generic door, double-sided, lower unpegged, repeatable action, with a front and back upper texture of SKINSYMB. What am I doing wrong?