My guess is that your triangles have no uv-coordinates. They should look
something like this:
smooth_triangle
{<0.480625,0,0.1>,<0,1,0>,<0.680625,0,0>,<0,1,0>,<0.680625,0,0.12253>,<0,1,0>uv_vectors<0.387569,0.545324>,<0.5,0.770187>,<0.362238,0.770187>}
Thomas
