Dynamic DNS with DHCP3 and BIND9

[Luis Murillo]

I have configured a DHCP server using dhcp3-server, it works correctly
since the PCs on the LAN obtain an IP. Now I would like to configure a
local DNS in order to have the hostnames to be in a database and only
have to remember a hostname and not the IP address. I have tried to
configure the BIND9 using multiple Howtos that I find on the Internet,
most of which say the same thing.
I'm using a MD5 key which is stored on /rncd.key. But I get this error
when I stop or restart the BIND9 server:
on /var/log/syslog:

Feb 14 00:47:14 bellatrix named[23528]: invalid command from
127.0.0.1#46590: bad auth


On the console:

lmurillo at bellatrix:~$ sudo /etc/init.d/bind9 stop
 * Stopping domain name service...
rndc: connection to remote host closed
This may indicate that the remote server is using an older version of 
the command protocol, this host is not authorized to connect,
or the key is invalid.
[ ok ]

What is wrong? How do I fix this and how do I get it to work? I have
tried resolving the hostname darkstar which has been assigned an IP by
the DHCP server, the PC says that it's hostname is darkstar.orion and I
have tried to ping that as well and it still returns host-unknown.

These are the configuration files:
dhcpd.conf: http://lcmurillo.spymac.net/dhcpd.conf
named.conf: http://lcmurillo.spymac.net/named.conf

The IP distribution goes:
Server: 192.168.0.1
ADSL Modem: 10.140.8.225 (Also the DNS which resolves internet queries)
LAN IP Range: 192.168.0.2 - 192.168.0.250
WAP IP: 192.168.0.251
Domain: orion
	The domain isn't actually registered, but is only used for LAN Domain

-- 
Luis Murillo <lmurillo at gmx.net>