Netscreen NS-5gt Set up help please

I have a NS-5GT wireless and I am trying to set it up on my home network through roadrunner , I cannot figure out how to get the DHCP to work. I want the untrusted port to recieve a IP from my modem. which my other router a D link 615 was doing . ive tried to set it in the webui but it never actually recieves a IP address that I can find , can anyone help

John
jwray1@ec.rr.com