Patch tool will not select

I was working with the patch tool and it worked fine. I decided to redo my work and reverted the image to start again. The patch tool will not select. When I try to select and move it around what I want to patch nothing happens and when I release I got "no pixel selected" dialogue box.

I trashed the photoshop plist but the problem is still there.

Anyone have any ideas

Dan

I continued to work on this and found that if I switched from the Wacom mouse I was using to a Wacom pen that patch tool started to work again and after starting with the mouse would even work when I tried the mouse.

Since then it has stopped working once, but switching to the pen got it back on track right away.

Dan