This isn't really a web related question so much as a Photoshop question, but hopefully someone can help me out with this little problem.

I want to lighten my cloud layer using a shortcut key command .. but for some reason when I click the SHIFT+CNTRL+F (or CNTRL+SHIFT+F) it isn't pulling up the option menu... Is there a way to find out if your keyboard is mapped properly?

I'm running Photoshop 7 on a PC.