DSL Modem->Wired Router->iMac G3 and Airport Express= No G3 Connection

Okay, so I have a iMac G3 and a SR MacBook. My DSL modem only has one port so I got a 4-port wired router so I could run my iMac G3 hardwired (It is not wireless compatible) so I set it all up and am running my AirPort Express in "Bridge Mode" but only the wireless is working my wired computer will not connect, it just give the message 'Could not find a PPoE server"...whats the deal?

This is how its set up:

Modem->Wired Router-> Airport Express
------------------->iMac G3