There's actually a bug in Bryce 5 (my version, anyway) where soft shadow works until you choose a preset sky in the skylab. After that, when you choose soft shadow it shows it in the skylab but not on the main screen. When you go back into skylab the check-box is unchecked. It doesn't bother me now because I never use skylab for lighting, but it royally p*ssed me off before!