Look to your error messages - they tell you what is wrong...
> right with the extra space in I get the following:
>
> ubuntu@ubuntu:~$ sudo mkdir /mnt/newroot
> ubuntu@ubuntu:~$ sudo mount /dev/hda7 /mnt/newroot
> ubuntu@ubuntu:~$ sudo mount -o bind /dev /mnt/sysimage/dev
> mount: mount point /mnt/sysimage/dev does not exist
^^^ That one ^^^
You've created a mountpoint /mnt/newroot & mounted /dev/hda7 on it, then
tried to access /mnt/sysimage...
