I think you have to click "Cntl+A" to select all your layers, lock them, press F2 to deselect everything and unlock the one you want to use.
Johnny Cuevas, Editor
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.