Pepakura problem

Hi guys, I'm going mad because of this problem. I have a .obj model and I want to import it into Pepakura 3. The model is perfect, but the program always open a model with an all-grey texture. I've tried to invert faces, but it show a strange repetition of thousand mini textures. And there is another fact: if I unfold the model, it put in the 2D panel a double unfolding work, one with the mini texture and one with the right texture. So, the model have right textures set in internal faces. What can I do to solve this problem and set textures in the right way (in external faces)?