Trying to understand reason for dhcp "no free leases" error

[Ric Anderson]

I have the following snippet from dhcp.conf
  host wxp285         { fixed-address xxx.105.130.199;
   hardware ethernet 00:15:60:5C:F3:70; }

  host wxp187         { fixed-address xxx.105.130.197;
   hardware ethernet 00:0C:76:01:7A:3B; }

and
  shared-network "130-net" {
   subnet xxx.105.130.0 netmask 255.255.255.0 {
   option routers xxx.105.130.1;
   option netbios-name-servers xxx.105.120.20,xxx.105.121.25;
   option ntp-servers xxx.105.121.28, xxx.105.121.29;
   option time-servers xxx.105.121.28, xxx.105.121.29;
   }
  }
The idea here is that any host which should be in the 130 net should
also have a host statement with a fixed address.  That's why there's
no range statement in the 130-net definition.  Yet in /var/log/messages
I see many instances of
Aug 19 13:20:42 murph dhcpd: DHCPDISCOVER from  via xxx.105.130.199: network 130-net: no free leases
Aug 19 13:20:43 murph dhcpd: DHCPDISCOVER from  via xxx.105.130.199: network 130-net: no free leases
Aug 19 13:20:43 murph dhcpd: DHCPDISCOVER from  via xxx.105.130.197: network 130-net: no free leases
Aug 19 13:20:44 murph dhcpd: DHCPDISCOVER from  via xxx.105.130.197: network 130-net: no free leases

We just switched dhcp servers to this platform (RHEL4, package dhcp-3.0.1-62.EL4) from
MultiNet DHCP on OpenVMS, and brought the configuration forward pretty much unchanged.
I suspect that xxx.105.130.197 got it's IP from the old server before the switch if
that matters.  The MAC addresses have been verified, and the Windows PCs in question
have the IPs that match the host definitions above.

Any ideas why a host with a fixed-address would cause a "no free leases" message?
Does there need to be a "range" with a couple of addresses to placate some part
of dhcp?

Thanks,
Ric