I am creating an icon and to apply shadow I am using the method to create similar overlapping layer, shifting one layer a little bit, selecting both of them and using the Minus Front error. For the background rectangle this method worked like a charm. But for a png I imported, the command give me an error saying "The filter produced no results. Please select two intersecting paths." Why is this happening and how to solve this ?
If anything else needs to be included please do tell. I am following this tutorial.