DHCP configuration in WinNT

How do I configure my DHCP server on WinNT to send my desired value for
the Host IP address (siaddr field) in the DHCP response from the server.
I tried changing TFTP Boot Host name etc. in the DHCP options found in
dhcpadmn.exe. Still the DHCP server sends siaddr value as 0.0.0.0.

Anyone who can help me out !?
Thanx.