Yes. The trick is to do either one of two things (or do both):
1) Don't delete the original textures in the TextureData[0]
2) Make sure that the new texture is of the right format. What I mean by that is whether the texture is say CMPR or RGB5485 (or whatever it is). Make sure the texture format is the same as when you imported the texture (for example, if you got a texture from a different character that was CMPR, make sure it is CMPR when you import it to the new character).
Oooh~! So that's why, I deleted the original texures.... Well thanks SDo0m~!