Tilemap painting difficulties

I've gone over the tutorial included in both the latest version of Torque Game Builder, as well as the outdated one on the wiki. But no matter what I do, I can't seem to get my image maps to show up under the "images" tab on the tile map editor. I follow the instructions to the T, including using the default test image. I set the image mode to "Cell," set the tile size to 128x128, etc. Still, nothing shows up when I try to paint my tile map. Does anyone have any clue what I could be doing wrong?