test if the skin is corrupt then, remap the textures in the wc3viewer; open the model, do ctrl+m, click on the texture it is using and click on change, then select the blp you want to give it. if it says invalid value, the skin is corrupt. if the skin's corrupt, get an already existing wc3 skin, and cnp you skin over everything, that should work. either that or the skin isnt in the same folder as the model.