FreeBSD 5.0 & device dsp

[Scoobie Ray]

Hi all!
I have FreeBSD Release: 5.0. I can't make device dsp.
 
In FAQ is wrote:
# cd /dev
# sh MAKEDEV snd0
Note: You can omit this step if you are running FreeBSD 5.0-RELEASE or newer with devfs(5) enabled.
 
I have wrote to command line:
# devfs rule add path dsp mode 666                
I have had this message:
devfs rule: ioctl DEVFSIO_RADD: Input/output error
 
Can you help me please?