No Public Key

I have been trying to add a repository from this site to Synaptic. I am using Ubuntu 7.10. When I add "deb http://ftp.wa.au.debian.org/debian sid main" or any other repository in the mirror list, after Synaptic has finished downloading the list of packages, it says "W: GPG error: http://ftp.wa.au.d

No Public Key

Some things I did not mention in the first email I have added at the end of this one. I have been trying to add a repository from this site to Synaptic. I am using Ubuntu 7.10. When I add "deb http://ftp.wa.au.debian.org/debian sid main" or any other repository in the mirror list, after Synaptic ha