Lost grey scale

When creating a mirror image I get to the step (in Mark's excellent toutorial) where you apply a grey scall form the drop down menu, the the drop down is not populated. All I have is a save as . . . Any idea how to get the drop down back?
Thank you
jim

1) Quit Motion.
2) Navigate to User/Library/Preferences.
3) Locate com.apple.motion.plist and delete it.

Thank you Mark, knowledge is power. Appreciate all you do for us.
Jim