"Switch off" monitor problem.

Hi! :-) I just installed TDE on a computer with Devuan stable already on it (through Trinity repositories for Debian based systems). I know this is an "as-is" release and Devuan is NOT officially supported for this version. Having said that, I have a problem switching my monitor off through software. At Configure KDesktop -> Display -> Power Control -> "Enable display..." is activated, but none of these 3 modes works. Also, giving from konsole "xset dpms force off", also fails. All the above, they're just activating the screensaver. Keeping always in mind, that this Devuan version is NOT supported, does someone have any hint on the above issue? TIA!!! :-) Giorgos.