Hi, I have been all over the Adobe forums and still can't get my CS6 clone stamp to work. I had the same problem in CS4 photoshop and thought if I upgraded it would fix it but I think it's got something more to do with the Yosemite and El Capitan upgrades that have fused the problem on my machine. Does anyone in the Mac Rumors forums know how to fix this problem or has come across it? I have used the clone stamp a thousand times previously, and since the upgrades it now says "Could not use the clone stamp because the area to clone has not been defined (option-click to define a source point". Very frustrating.