Problem exporting

I have been working on a model for gmod and when I export it I get:
WARNING: Material “XX - Default” does not appear to have a diffuse bitmap texture. Skipping mesh.
anyone knows how to solve it?

Bump. Bump bump bump.

I had this problem with the e102gamma i took a stab at the way i fixed it was exporting the actual model as a .obj, re-importing back into max and then re-applying the textures, i don’t know why it does it I hope ya can export the model as a .obj or anything like that if not then i dunno what ya can do hope this helps.