Have an issue that has been bugging me for years with previous versions of PSP and the newest .

Why is it that sometimes I create a transparent gif and it works whereas others it doesn't, in no particular pattern?

Frequently, I'll have an image that I wish to set transparency on, set the transparency, it appears to be there, save the file and when I next load it its no longer there.

Is this a known issue and easy to solve? Does it depend on the graphic, the palette, the number of colours.... ?

Cheers

James