[igraph] Problem in running example

[Lorenzo Isella]

Dear All,
I am trying to run on my machine (Debian testing, x86 architecture, 
igraph installed from Debian repository) the example about Cairo 
transparency you can find at

http://cneurocvs.rmki.kfki.hu/igraph/screenshots2.html#3

but this is the output I get:

Error in eval.with.vis(expr, envir, enclos) :
 could not find function "layout.norm"

I have no idea about what is going on; I installed the Cairo library 
from source with

R CMD INSTALL Cairo_1.4-4.tar.gz

and I got the source from

http://cran.r-project.org/src/contrib/Cairo_1.4-4.tar.gz


Any idea of what is not working?
Cheers

Lorenzo