[R-sig-Debian] cannot upgrade to R 2.9.1 in Ubuntu

[Luis Ridao Cruz]

R-SIG-Debian help,

At the moment the R version installed on my machine is 2.8.1. (Ubuntu 9.04)
I wish to upgrade to  R 2.9.1.

I did:
$ sudo apt-get upgrade

but R is not upgraded although the "sources.list" file is updated with:

deb http://cran.ii.uib.no/bin/linux/ubuntu jaunty/

When I run from the terminal I still get:

$ R
R version 2.8.1 (2008-12-22)
Copyright (C) 2008 The R Foundation for Statistical Computing
ISBN 3-900051-07-0

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale
........
........


Thanks in advance