Since switching from Chrome, I can't print .pdf attachments directly from my gmail. Please help.

It used to be (in Chrome) that I could view a .pdf attachment in gmail and from there print. Now in Firefox, when I view a .pdf attachment the print option is there and the print dialogue box comes up when I click it, but once I hit "OK" nothing comes out of the printer. I can print emails and other items, so it's not a printer connectivity problem or a problem with the print setup in Firefox. The only items affected are .pdf attachments in my gmail account. I've tried switching .pdf readers and turning off Protected Mode in Adobe. Please help!