make sure that you have absolutely no color in the map at all, try resizing to 512x512 or flatten the image incase theres any little stray things. also instead of saving directly to the folder, try saving it to your desktop first then move it to FeralHeart<media<terrains and then load it on the map maker and see what happens. if all else fails... you can look in the map maker tutorials and check to see if you had done anything wrong in the making that altered it somehow.