Custom Terrain Problem

This makes me feel stupid but I made a custom sand texture for Sunken Ruins.
Its a white san, but when I put in the exact path that is in war3x.mpq it won't show. At first I thought the change was to subtle, so I made it completely blue. Still doesn't work. The path I use is TerrainArt\Ruins\Ruins_Sand.blp
What am I doing wrong?

You have to restart the editor to notice any changes.