Bump Map on a DIF

I'm trying to get a bump map applied to a texture on the exterior of a DIF. Is this supposed to be working properly? I've create a material entry for the texture and applied the bump map but I can't see any difference at all. I've even tried applied other effects like specular highlighting and still can't see the bump map affecting anything.

Here's the DIF I'm applying the bump map to:
and here's the bump map for that brick texture:
and here's my Material definition:

new Material(Old_Wall2_256x256)
{
   baseTex[0] = "Old-Wall2-256x256";
   bumpTex[0] = "Old-Wall2-256x256_bump";
};