Sleep not powering off monitor

John Seal wrote on :

Hello.

I have read http://til.info.apple.com/techinfo.nsf/artnum/n20181 about the difference between Energy Saver sleep, which blanks the video but not the sync, and Sleep Menu sleep, which blanks the sync too, but when I choose Sleep from the special menu the monitor doesn't power down.

MacDim can power it down, so I know both the monitor and the computer support it, so why can't Energy Saver power it down?

This is on a G4 533 single processor, 384 MB, Mac OS 9.1, CarbonLib 1.3.1, Energy Saver 3.0.4.

Any clues?