dynamic DNS updates

Hi there,

I am having some difficulties getting dynamic DNS running on a new FC4 server
I just built.  Some web searching has not really given me the results to
figure out what is broken.  I was hoping somebody on this list could assist me
with troubleshooting it.  I have replaced the hostnames and IP address to
protect the innocent.

I am trying to get the A record for machine.hostname.com to be regularly
updated to my primary name server at 111.111.111.111 .  But this appears to
not be happening.  

---- snip ----

send host-name "machine.hostname.com.";
send fqdn.fqdn "machine.hostname.com.";
send fqdn.encoded on;
send fqdn.server-update off;

key machine.hostname.com {
    algorithm HMAC-MD5;
    secret "a;dflkja;sldkfja;lkdjq;wlekjr;qlkwejr;lqkwjer;lkqjewr";
}

zone hostname.com {
    primary 111.111.111.111;
    key "machine.hostname.com";
}

interface "eth0" {
    send host-name "machine.hostname.com.";
    send dhcp-client-identifier 00:C0:F0:1F:21:E2;
    send dhcp-lease-time 3600;
    supersede domain-name "host.hostname.com hostname.com";
    prepend domain-name-servers 127.0.0.1;
    request subnet-mask, broadcast-address, time-offset, routers, domain-name,
domain-name-servers, host-name;
    require subnet-mask, domain-name-servers;
    script "/sbin/dhclient-script";
}

--- snip ---