I'm having a slight issue with uploading it. I based it on the one that comes with it, and I can't figure out how that one works. From what I can gather, multiple things are transparent. Whenever I try uploading mine, it causes it to look weird, and it even keeps the colour box that doesn't show up when looking at a preview of the default window skin =/
Can you please show us the windowskin you are using? It might be that there are multiple transparent colors, or that the pic is saved as a JPEG.