RADIUS - Airport Setup for 802.1x

Hello.
I thought it would be very easy thing to setup RADIUS on a Mac OS X 10.6 Server to use it for 802.1x authentication for the WiFi network.

Adding a base station to the RADIUS Server is quite easy and the settings on the Airport are changed automatically.

But if I try to connect from a Laptop to the Airport I don't get a connection.
In the RADIUS log I can see the following:

Ignoring request to authentication address * port 1812 from unknown client 192.168.178.10 port 65527

I maybe someone able to provide information about the proper setup?

Thanks,
Maik