Canon Printer on WIFI net work

That isn't a wifi printer - how do you connect it - print server or USB port on router, etc?

Has it ever worked on the wifi network?

Since it is a USB printer, Canon only makes USB-only drivers for it.

If you have the printer connected via Airport or Airport Express, Apple's software makes the network connection possible. But other brands of router and print server don't have Apple's USB-via-network capability.

If you want to connect using all the standard OS X connection protocols, you have to use a driver that can do so. Install Gutenprint open source drivers:

http://gimp-print.sourceforge.net/MacOSX.php

On the computer with the Canon connected to it that the other Mac can't access, go to System Preferences > Sharing & select "Printer Sharing" from the list on the left. Make sure that the Canon appears on the "Printers:" list & has a checkmark beside it, & in the "Users:" list that there is a suitable entry for it. For example, if you want "everyone" to be able to use it, make sure the "Can Print" popup item is set, rather than "No Access."

You can click the question mark icon in the preference when it is set to printer sharing to see the Share your printer help topic, with more info about this.