Problems creating a linux domU

[Juan RP <juan%xtrarom.org@localhost>]

Hi, I'm trying to boot ttylinux... but there is one error:

[juan@Mandylion][~]> sudo xm create -c /etc/xen/ttylinux
Using config file "/etc/xen/ttylinux".
Error: Error creating domain: vbd: Device not found:  sda1
[juan@Mandylion][~]>

The configuration file used was:

kernel = "/home/juan/xen/vmlinuz-2.6.10-xenU"
memory = 256
name="Linux-XenU"
cpu = -1   # leave to Xen to pick
nics=1
disk = ['file:/home/juan/ttylinux-xen, sda1,w']
vif = [ 'mac=aa:00:00:50:02:f1, bridge=bridge:bridge0:rtk1' ]
root = "/dev/sda1 ro"

Any hint?

Thanks.