Server Power Off

[Sysadmin]

I installed FreeBSD 4.7 on my server with Intel SE7500CW2 motherboard
 and Intel Xeon 2000 Mhz.
I have added following string in /etc/rc.conf file:
                apm_enable="YES" 
and in kernel configuration file:
                device apm0 at nexus? disable flags 0x20
Hovever shutdown -p now does not turns off the power.
             Thanks in advance, Vladimir Konnov