[Koha] ubuntu amd64

I am trying to install koha on a ubuntu 6.06 amd64 machine. When I add these lines: #for Yaz Toolkit deb http://ftp.indexdata.dk/debian indexdata/sarge released deb-src http://ftp.indexdata.dk/debian indexdata/sarge released I get this when I do an apt-get update: Err http://ftp.indexdata.dk indexdata/sarge/released Packages 404 Not Found and then a little farther down: Failed to fetch http://ftp.indexdata.dk/debian/dists/indexdata/sarge/released/binary-amd64/P... 404 Not Found If I do a apt-get install libyaz it upgrades it to 2.1.8 which will not work. Any help suggestions are desperately appreciated.