[R] Installing R on Ubuntu 8.10

[Maria I. Tchalakova]

Hi,

I am trying to install R on Ubuntu 8.10. I have added this line:

deb http://cran.at.r-project.org/bin/linux/ubuntu intrepid/

in my /etc/apt/sources.list file. However when I "Reload", I get the
following error message:
W: GPG error: http://cran.at.r-project.org intrepid/ Release: The
following signatures couldn't be verified because the public key is
not available: NO_PUBKEY D67FC6EAE2A11821

I have tried different mirror sites, but the result is the same. There
is nothing written about public keys on the download page:
http://cran.at.r-project.org/

Then, I have tried (after I added the line to the
/etc/apt/sources/list file) not pressing "Reload", but "Close", and I
have written in the console:
sudo apt-get update

but I received similar message again:
....
Reading package lists... Done
W: GPG error: http://cran.rakanu.com intrepid/ Release: The following
signatures couldn't be verified because the public key is not
available: NO_PUBKEY D67FC6EAE2A11821
W: You may want to run apt-get update to correct these problems

Do you know what the problem is, and what should I do? Thanks in advance.

Maria