Is this a PNG that worked ok previously or a new one? There's a huge difference. I can't be of any assistance if it was previously okay, but if it's a new one you created, the problem is probably in the way you saved it. During the save process, you are asked to choose a background colour, but for transparent backgrounds you may have to make parts of it transparent during the photo manipulation stage. It depends on the software and the quality will vary from program to program.

read here please: http://www.oxwall.org/forum/topic/17417 do the search before posting