I think the reason the model doesnt show up is the 2nd skin, especially if its a normal map tga. I had this problem several times when exporting models from Max that I had texture baked. It appears that the 2nd skin got used as a transparency layer, making my entire model almost completely transparent.

Try removing the 2nd skin to see if it resolves the issue.

If your trying to implement some transparencies in your skin, you have to set a z buffer variable. I can't remember the exact code at this moment, but im sure someone here can remind me

Hope that helps