I have a CD and Floppy setup of M0n0wall on a system.

If I run setup for the ADSL line into the wall box, the ETH0 card fires up
and sees the WAN. If I setup the D-Link router segment of my LAN, the wall
box fires up ETH1. BUT, if I try to add a stand alone system ( I am trying
to set this one up as a 1:1 NAT for it's own IP) the ETH2 card on the wall
system is dark. If I plug the stand alone system into the D-LiNK router - No
PROBLEM the router sees the computer and assigns and IP for is on the
router.
I have tried to set this up in all three ETH cards on the wall box, none of
them light up when the stand alone box is plugged in.

WHY? is the firewall not seeing this stand alone system? did I miss a step?
Why would this happen when the other WAN and LAN setups fine ?