freebsd error

[marco di sano]

hi,
I have downloaded the freebsd images from
http://wiki.freebsd.org/AdrianChadd/XenImages/ , but I tried to boot the
machine with this configuration file:

bootloader = '/usr/lib/xen-3.0.3-1/bin/pygrub'
memory = 256
name = 'freebsd_current'
vif = [ 'bridge=xenbr0' ]
disk =
['phy:/dev/VolGroup00/FreeBsdRoot,sda3,w','phy:/dev/VolGroup00/FreeBsdSwap,sda3,w']
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'

but I had this error(this is the output):

Traceback (most recent call last):
  File "/usr/lib/xen-3.0.3-1/bin/pygrub", line 481, in ?
    g = Grub(file, isconfig)
  File "/usr/lib/xen-3.0.3-1/bin/pygrub", line 147, in __init__
    self.read_config(file, isconfig)
  File "/usr/lib/xen-3.0.3-1/bin/pygrub", line 338, in read_config
    raise RuntimeError, "Unable to read filesystem"
RuntimeError: Unable to read filesystem
No handlers could be found for logger "xend"
Error: Boot loader didn't return any data!
Usage: xm create <ConfigFile> [options] [vars]

Someone can tell me the correct way to use the frebsd image and boot it?
Is there something to change in my configuration file?

Thanks
Marco