Custom model's don't display

[techniquees]

I followed Glitchy's guide to custom models. And every step went fine as far as I'm aware. I UV mapped where needed, converted the 3ds to m2, assigned the BLP file and stuck it in an MPQ. When I open any of these models in wow model viewer, I get a C++ error pop up, if i click ignore it persists for 3 or 4 times then stops and the model displays fully textured in the window.

But when I try and see it ingame there's just nothing there. I tried replacing a race with one of the custom models and the login screen with that race selected is completely black. I can't seem to find anyone with the same problem so perhaps theres something I'm doing wrong?