[ULTRAMONKEY-USERS] GPG key problem on ubuntu 6.06 server

[Rick Graves]

Hello,

I have a ubuntu 6.06 server and I am following the
Debian instructions here:

http://www.howtoforge.com/high_availability_loadbalanced_apache_cluster

That recommends adding these to lines to sources.list:

deb http://www.ultramonkey.org/download/3/ sarge main
deb-src http://www.ultramonkey.org/download/3 sarge
main

When I do apt-get update, I get a GPG error:
http://www.ultramonkey.org sarge Release: The
following signatures couldn't be verified because the
public key is not available: NO_PUBKEY <hex number>

OK, ubuntu is not Debian -- is that the problem? 

What would be a quick fix?

Thanks,

Rick