Can you verify you have libgnomeprint2.2-0 version 2.12.1-3ubuntu2 installed as Anté suggested (dpkg -l libgnomeprint2* should give the answer).
Can you try if n-up printing from a command line works by printing a multipage pdf document, e.g.: $ lp -d Canon -o number-up=4 file.pdf
Can you verify you have libgnomeprint2.2-0 version 2.12.1-3ubuntu2 installed as Anté suggested (dpkg -l libgnomeprint2* should give the answer).
Can you try if n-up printing from a command line
works by printing a multipage pdf document, e.g.:
$ lp -d Canon -o number-up=4 file.pdf