I have both photoshop and illustrator open. I create an image in photoshop and select the object and copy. i then open up illustrator and paste it into my project. i use that image along with a square that i've created in illustrator. i select both and click the divide option in the pathfinder pallette. it does not divide the photoshop image. am i supposed to do something to this image so that it will cut with the divide command?