Your default ccbill affiliate links will/should always work, but you'll probably want to go into your ccbill admin and change the redirect url and make/upload a new tour for it with the standard ccbill signup buttons. Pretty sure if you send them to your nats tour their codes are not going to work/track.
We don't use nats but this is how it works with our own script.
http://refer.ccbill.com/cgi-bin/clic...0000&PA=810145
http://www.bikinivoyeur.com/affil.php?affilid=518
Notice each has their own url.