I've been trying to make a map in the mission editor, but unfortunately a problem with the editor has been stopping me from doing pretty much everything. When I try to load a texture that's not a default, it appears white, and when I use a default texture to cover the map, the mission editor doesn't save the texture so it reverts to default grass when I come back to the map later. I don't know why the forget it's doing this and I don't know how to solve it.