Unable to go to suspend mode on Sony VAIO VGN-S4XP

[Stanislas SABATIER]

Hi all,
I managed to install freeBSD on an old laptop, a Sony VAIO VGN-S4XP.
Installation is OK
wifi card works.

BUT, I'm unable to go to suspend mode : when I acpiconf -s 3 , the 
system freezes : the screen is on and the hard disk's led is 
continuously on. Nothing more happens.

Is there anybody there who succeeded to turn this laptop to suspend mode 
?

Thank you for your help.

Regards,
Stan.