SBS 2003 DHCP Server with Router

My SBS 2003 Server is not giving the client computers an IP address. The only way I can get them on the internet is if I manually configure the network adapter.

This is how I have it set up.
The modem goes to the router and from the router it goes to the server and all the other computers. I have the DHCP server off on the router and the clients still cannot get an IP address from the DHCP server on the SBS 2003 Server.

I have ran the wizard on the SBS 2003 Server a few times and went through all the settings to make sure they are all configured right.

Does any one have an idea of what the problem could be?

Thanks In Advance!