I am using PS CS 5 and would like to know why the color replacement tool will not work on some images. I can't give any specific examples of when I have not been able to get it to do anything. I also often get a situation of not liking the first color that is replaced but no matter what subsequent color I select, the tool continues using the first choice. If it makes any difference, I am using Win 7 Pro, 64 bit.