Jump Raven/Lunicus in Classic Environment

Hi,

In the past i've tried to play two old games by the names of Jump Raven and Lunicus on my eMac with Classic installed. Most of my old games ask to be played in 256 colors and that isn't a problem but, with Jump Raven and Lunicus, I change the monitor to 256 colors and when I click on either game a message pops up that says:

Fatal error: can’t switch to 256 colors.

Am I doing something wrong? Help would be appreciated because I would like to play these two old games again.