[CentOS] idle timeout on Centos6

Dear All,

I'm using Centos6 with Gnome Desktops. As far as I can tell the default idle timeout is 5 minutes.

I try to set this to 15 minutes with this command:

gconftool-2 --direct --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory --type int --set /apps/gnome-screensaver/idle_delay 15

This doesn't change the value in System-Preferences-Screensaver. And when timing the idle-timeout, it's still 5 minutes.

Opening gconf-editor, I cannot find the standard 5 minutes, the standard here is 10 minutes under /apps/gnome-screensaver/idle_delay

What am I doing wrong?

Greetings, J.