Are you sure it's 513x513 and that you haven't used separate layers? Try checking that and see what happens. Also make sure that the colours are correct. If you're using GIMP than make sure you've flattened the image instead of merging it, merging the layer reveals the transparency and that tends to be the problem sometimes.R 225, 0, 0.G 0, 225, 0.B 0, 0, 225.