NFS support for booting live ubuntu 15.04

[Hamjam]

hello ipxe team,
I am new user of ipxe
I've downloaded the last version of ipxe and made undionly.kpxe for chainloading with an embedded script :
#!ipxe
dhcp
set server_ip 192.168.1.75
set nfs_path /srv/nfs/ubuntu 15.04
kernel nfs://${server_ip}${nfs_path}/casper/vmlinuz.efi || read void
initrd nfs://${server_ip}${nfs_path}/casper/initrd.lz || read void
imgargs vmlinuz.efi root=/dev/nfs boot=casper netboot=nfs nfsroot=${server_ip}:${nfs_path} ip=dhcp splash quiet -- || read void
boot || read void

I've set up my nfs server service and it is okay I think
But when I want to set a client it replies that:
Could not start download: Operation not supported(http://ipxe.org/3c092003

Please answer me if ipxe supports nfs or not
Sorry for silly question