What size did you use for the icon? They usually should not exceed a certain size, as apparently that can cause them to lose their transparency. A good size for icons is 32-128 pixel, I believe.
i see, this is 180x180. I will resize it and update the thread as to whether this fixes the issue.
EDIT: Unfortunately, this did not fix the issue. I resized the icon to 64x64 and there was no change in the result.
