Fax Setup Problem: Networked MacBook can't find HP 2160 Fax

I have a recent MacBook Intel Duo OS X (10.4.10) that I have connected to base station via Airport. (Airport Extreme Base station, works fine for everything else) Base station is connected to cable modem (WAN) and Intel iMac is connected to base station via Ethernet cable. Network works fine.

I have an HP 2160 All-in-One Printer/Fax/Scanner connected to base station via USB. I just installed HP's bloated driver package on my Airport networked MacBook.

I can print fine via Airport networked MacBook, but I can't get the MacBook to find the fax (on printer setup) to allow me to send a fax via the HP 2160. The HP 2160 works fine as stand-alone fax (it's hooked up to phone line, has it's own internal fax modem).

Any suggestions?

Thanks.