d-i preseed & lvm

[rattking]

Hi all I am trying to automate installation for many boxen using pxe boot and a preseed.
If I go by the predefined partitioning recipes it works. but I need more control over the filesystem layout and lvm naming conventions.
With this expert recipe d-i errors out with "No root file system is defined" and I cant figure out why.
d-i partman-auto/disk string /dev/sda
d-i partman-auto/method string lvm
d-i partman-auto-lvm/new_vg_name string dom0
d-i partman-auto/expert_recipe string \
dom0 :: \
256 256 256 ext2 \
$primary{ } $bootable{ } \
method{ format } format{ } \
use_filesystem{ } filesystem{ ext2 } \
device{ /dev/sda } \
mountpoint{ /boot } . \
100 1000 1000000000 xfs \
$defaultignore{ } \
$primary{ } \
method{ lvm } \
# device{ /dev/sda } \
vg_name{ dom0 } . \
500 10000 1000000000 xfs \
$lvmok{ } \
in_vg{ dom0 } \
lv_name{ root } \
method{ format } \
# device{ /dev/sda } \
format{ } \
use-filesystem{ } \
filesystem{ xfs } \
mountpoint{ / } . \

lvdisplay shows /dev/sda2 is in vg dom0
pvdisplay shows /dev/dom0/root is created and the right size.

I would also like /boot to be on lvm as well but I cant even get this working.
I have tried various things and no expert recipes involving lvm have worked.
any help would be great appreciated as I am stuck.
TIA.