auto logout

Hi,

We have a Fedora Core 5 server installed and users get a kdm login 
window from
other machines. They log into kde through this window. But they also 
frequently
forget to logout of kde so,I'd like to be able to  automatically log 
them out after
a certain period of inactivity.

Here's my ScreenSaver section in /usr/share/config/kdesktoprc

[ScreenSaver]
AutoLogout=true
AutoLogoutTimeout=10
Enabled=true
Lock=false
Priority=19
KBlankscreen.desktop
Timeout=10

The screensaver comes on after 10 seconds, then the autologout progress 
bar appears
after  10 seconds, all as expected, but, when the progress bar counts 
down to 0 seconds
nothing happens, no logout nothing. If I move the mouse or hit the 
keyboard I'm back in
my session. Why don't I get logged out?

Any ideas?

Thanks

Sami