dhcp issues wrong subnet to clients

I am setting up a W2Kserver with AD,DHCP,DNS,WINS. Clients can see server but server can’t find path to client. The server has a static subnet of 255.255.0.0 It assings a subnet of 255.0.0.0 to clients. If I use static IP addresses on clients withthe 255.255.0.0 subnet, server can find client. What’s going on?