Null textures?

Dear All, I''m trying to load a X file I''ve got, and I''m having some problems. Every so often, it trows up a texture that has a blank filename(""). When I load the Xfile in the mesh viewer however, it loads fine. In my program, I''ve set it so that whenever a null filename occurs, I can set the texture to the last one loaded, and then it looks like what occurs in the mesh viewer. Is this whats going on? Is it standard behviour? Thanks, Jesse