acpid script can't connect to X Server in FC4

[frederic.bauchet at voila.fr]

On my thinkpad T23 I use hotkey Fn+F3 to switch off screen on a Fedora Core 4 with ibm-acpi module.

The script is :
export DISPLAY="localhost:0.0"
xhost +
xset dpms force off

Into /var/log/acpid I get the followind logs :
_X11TransSocketOpenCOTSClient: Unable to open socket for tcp
_X11TransOpen: transport open failed for tcp/localhost:0
xhost:  unable to open display "localhost:0.0"
_X11TransSocketOpenCOTSClient: Unable to open socket for tcp
_X11TransOpen: transport open failed for tcp/localhost:0
xset:  unable to open display "localhost:0.0"

I have enable the tcp socket of the X server with gdmsetup and the X server is listening on port 6000.

If I use the same script as root, it works fine.

Dos anyone have already resolved that kind of problem ?

Thanks in advance for your help

Frédéric