cannot send fax to shared usb modem

I have a Mac Mini, with 10.6.8, with an attached USB Fax Modem. This fax modem is shared in Print Preferences. I cannot send a fax through this shared fax modem from the 10.8.5 Mac Mini Server on the LAN. The print Dialog recognizes the fax modem and the appropriate fax dialog displays allowing me to enter the phone number, select a cover page, etc. The fax does not appear in the 10.6.8 print queue. The fax modem sends faxes when sent from the 10.6.8 Mac Mini - the machine it is attached to.

Does someone know what is preventing a document being faxed from the 10.8.5 machine through the shared fax modem on the 10.6.8 machine, and how to correct this problem?

Thank you.

Lewis Lorenz