problems with xfsm-shutdown-helper on solaris

[Alessio Cervellin]

I got a XFCE4.2.1 fully working (at least it seems so) on Solaris 11 
Nevada b22 x86 32bit.
I configured the sudoers to allow users to shutdown/reboot the system, 
and it should be ok because these options are not grayed anymore.
Anyaway, whether I exit from XFCE by choosing "reboot the computer" or 
"turn off the computer" the behavior is always the same of "quit current 
session": what i get is just a logout from the session and not the 
system poweroff.
Same problems if I login as root too, so it's not a matter of sudo.

By typing "xfsm-shutdown-helper" as root i get the following error:

XFSM_SUDO_DONE
FAILED

By typing "echo POWEROFF | xfsm-shutdown-helper" i get the following error:

Failed to execute child process "/sbin/shutdown" (No such file)
Segmentation Fault

So i linked it to the right path:
ln -s /sbin/shutdown  /usr/sbin/shutdown

But typing again "echo POWEROFF | xfsm-shutdown-helper", i get:
XFSM_SUDO_DONE FAILED

Of course, the commands "shutdown" or "poweroff" alone work fine.

Can anyone help?