[all variants] problem with grub2

I am having trouble upgrading a system it had ubuntu 12.10 9#onit . it has no CD drive and despite being bios capable refuses to boot from a pendrive.

So I have downloaded an iso and I am trying to boot from it.
This is my 40_custom file

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
menuentry "Ubuntu ISO"{
set isofile="/home/neil/Downloads/ubuntu-14.04.4-desktop-i386.iso"
loopback loop(hd0,1)$isofile
linuxefi(loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=$isofile nopromp
t noeject
initrdefi(loop)/casper/initrd.lz
}

previously I tried linux and initrd as commands

The menu come up but when I chose the option it gives two Can't find command errors on those lines which I have varied as speified above.

Can anyone help please?