When i try in the logout menu to put the computer to standby or hibernate that does not work. I get the feedback (in the logout menu): "Not authorized". And im going only to the Xscreensaver.

Configuring the (xfce)powermanagement does not have any affect. Either suspend or hibernate (e.g. at When close lid) bring only to Xscreensaver (like above).

Doing in the terminal:

"sudo pm-hibernate"

or

"sudo pm-suspend"

that works.

Any ideas what and where i have to correct?

TIA