I'm trying to make a path (outlined in http://i51.tinypic.com/2m3ml9i.png) using the texture TerrainMud03 in an exterior cell. When I try to apply it, nothing seems to happen. I hold down the right-mouse-button, drag it around, but nothing happens. Still the same grass texture as was there before. I click "i" to see if there are too many textures, and I see that http://i54.tinypic.com/b7b2w1.png, despite not being visible anywhere on the landscape, and it was not previously listed there before I attempted to 'paint' the texture on the landscape.
I'm confused.