grub cannot find iso file

Hi. I am trying to boot an iso file through grub
I followed the example given here: https://help.ubuntu.com/community/Gr...ot#Downloading

Code:menuentry "Ubuntu 12.04 ISO" {
set isofile="/home/<username>/Downloads/ubuntu-12.04-desktop-i386.iso"
# or set isofile="/<username>/Downloads/ubuntu-12.04-desktop-i386.iso"
# if you use a single partition for your $HOME
loopback loop (hd0,5)$isofile
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject
initrd (loop)/casper/initrd.lz
}and then I did the necessary modifications:

Code:menuentry "Ubuntu ISO" {
set isofile="/media/34GB/videos/lubuntu-16.04.6-desktop-amd64.iso"
# or set isofile="/<username>/Downloads/ubuntu-12.04-desktop-i386.iso"
# if you use a single partition for your $HOME
loopback loop (hd0,6)$isofile
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject
initrd (loop)/casper/initrd
}Yet I receive when I try to boot from the new menuentry:

Code:error: FILE not found
error: no such disk
error: you need to load the kernel firstAfter that I checked all the details that I changed from the internet text, but everything seems to be ok.

The iso is indeed in /dev/sda6. I did a copy&past from the path to the isofile to be sure no typing error is present.

I did mount the iso file and checked the names of the kernel and initrd. They are indeed "vmlinuz" and "initrd" and are in a "casper" dir