Zyxel 660HW Wireless DHCP problems

I've a problem when connecting to my accesspoint (Zyxel 660HW). It doesn't
relay DHCP or even traffic.

Situation: Modem/Router/Accesspoint/Switch (Zyxel 660HW) is connected to
Internet, DHCP is off, Windows 2003-server (Small Business 2003 SP1) is
connected through the switch and running DHCP.
Wired it's all runnin great. Wireless I get connected to the Accesspoint
and that's it, no DHCP. There even is no traffic between pc/laptop and
accesspoint. Even when I make a static ip, it doesn't work.

I've contacted Zyxel and they told me to telnet and change a general
setting Bridge to On. So I did, it doesn't work. I've looked further and
discovered that multicast was off. For my knowledge DHCP-requests are
multicast (right?). I put in on. No result.
Of course I've tried everything else; DHCP-Relay on/off, firewall on/off,
wirelless standard settings (no WEP/WPA).

Anyone else?? I would very much appreciate it.

Georgie