I'm not sure what you mean by "Flatten" but I do know is that if you save them as a png, the images won't work unless you have a coding such as transparent to go with it. Usually regular jpgs are what really makes a preset show. If you want, you can try to send me the preset files, and I can try to fix it for you if I can. If you want me to do this, you need to compress the files in a zip folder and send it to me in mediafire if you want me to try to fix it for ya.
OR... It could just be something wrong with the coding? Like did you arrange the coding differently?