struggling with adding machines

[nigel barker <tech@hiroshima-is.ac.jp>]

Hi everyone
I have a brand new SL3 Tjener and a brand new SL3 Ltspserver. Both are 
virgin fresh.
I logged in to lwat on Tjener to add the ltspserver as a machine.
I entered the MAC address very carefully (and rechecked many times 
since) and the name ltspserver02. Then domain:intern and IP:10.0.2.12 
both popped up automatically.
I made it a member of ltsp-server-hosts, saved, and restarted dhcp3-server.
When I booted the ltspserver it came up as dhcp155, bound to 10.0.2.255, 
and there was an error:
unable to update hostname from DNS.

To check, I entered a machine account for ltspserver01, which is a SL2 
server. The same thing happened - it came up as dhcpsomething instead of 
ltspserver01, and it didn't get the IP shown in lwat.

Since I don't know what I'm doing, I restarted bind also, and then 
finally rebooted tjener. The same thing keeps happening.

what am I doing wrong?

thanks!

nigel