make boot cdrom pb:

Hi,
I'm configuring FAI v3.2.1. I ran fai-setup without any pb. Now I'm 
trying to create a bootable cdrom running this command :
make-fai-bootfloppy -f /tmp/fai_floppy.img -i /tmp/fai_iso.img 
"FAI_FLAGS=sshd,createvt"
but it fails with this error message :
ls: /srv/fai/nfsroot/boot/vmlinu?-*: not found
Creating an ext2 filesystem on floppy device /tmp/fai_floppy.img.
Creating the boot floppy with grub.
can't find `/srv/fai/nfsroot/usr/lib/grub/i386-pc/stage?'

When I look into /srv/fai/nfsroot , I have only one directory named "live".
To find the nfsroot files, I need to look at 
/srv/fai/nfsroot/live/filesystem.dir/

Is that normal ? How can I do to create a bootable cdrom ?

thanks for your help ;o)

JPB