I could be wrong, but make sure everything you imported having to do with the model in question looks like this:
EVERYTHING ending in .blp needs to be changed from
war3campimported\(filename).blp --> Textures\(filename).blp
the actual model file that ends in .MDX will remain the same:
war3campimported\(filename).MDX
DON'T change the .MDX file.
If that doesn't work, open the war3 viewer, open the .MDX model(the one that is actually a picture) click on 'current file' then click on 'Used texture names'. Then, simply change all of your imported files to look exactly like the ones in the drop box on the war3 viewer.
Also, if you are making a campaign, open the campaign editor, click 'Edit' export files. Export your files to their own organized folder. Then, open the object manager. Click on 'File' import files. Hit okay, and then double-click on the folder you just made when you exported the files from the campaign editor. Wait for everything to load. Save your game. Exit and re-enter the Warcraft Editor if necessary. And don't bother testing your map with the 'Test' button. Just open Warcraft, and play your scenario. If all else fails, my problems ended when I read the tutorials located on this web site. The ones in the "2D art" section helped alot. Good luck to you!
