Alright guys here it is

So please first install easy-chroot (you don't need easy-debian if you don't wanted)

Uninstall the previous .deb file (if you installed it)

Remove all ubuntu related files including /home/user/MyDocs/ubuntu-m5-v1.2.img.ext2

Uncompress the file ubuntu.img.ext2 in your n900 or in your computer (recommended) and transfer it to MyDocs or in your sdcard

Install ubuntu-N900.deb with app-manager or with dpkg -i ......

Please feedback any result.

Thanks