Perhaps I'm doing something really wrong, but my clone tool does not appear to work at all. I've selected the tool, I've done the alt+click to set the crosshairs on my clone source, but whenever I drag over the object I want to clone out, absolutely nothing happens, no changes are made to the image. Opacity and hardness are set to 100%, so I really can't figure out what the problem is. Any suggestions? Blemish removal tool doesn't have any effect either.