Have installed and configured ser and everything works fine until I turn on authentication. I have a suspicion my problem resides in my route logic. This is how I modified the default ser.cfg file:

route{
        if (!mf_process_maxfwd_header("10")) {
                sl_send_reply("483","Too Many Hops");
                break;
        };
        if (len_gt( max_len )) {
                sl_send_reply("513", "Message too big");
                break;
        };
        rewriteFromRoute();
        if (uri=~"mkc.co.za") {
                if (method=="REGISTER") {
                       if (!www_authorize("mkc.co.za", "subscriber")) {
                               www_challenge("mkc.co.za", "0");
                               break;
                       };

                        save("location");
                        break;
                };
                if (!lookup("location")) {
                        sl_send_reply("404", "Not Found");
                        break;
                };
        };
        if (!t_relay()) {
                sl_reply_error();
        };
}

Any ideas? Have gone through all the sql confs and sql seems fine (default installation), only added one user with serctl.