Yesterday I had a customer whose daughter had an older iMac who wanted to print over the network to a printer hooked to a PC.
The PC was an older Dell and the printer was an older Dell All-In-One. Dell printers are made by Lexmark, the printer software is made by Lexmark, but the printer drivers are written by Dell.
(Drivers are small pieces of software that tell a piece of hardware how to operate; in this case how to print a document.)
It turns out that the Dell AIO did not have Macintosh drivers. The Mac could see the PC (who was acting as a print server), could send the print job to the PC, the printer would say “printing” and yet nothing happened.
The moral of the story: make sure your PC’s printer has Mac drivers available.