i have an HP AirPrint printer, my iPhone 4S (both) and my iPad (both) will print yet my new MacBook Pro will not as it says the printer is not online.

One common cause for this symptom can be caused from the printer setup. If you had to connect the printer to the Mac via USB cable so that you could run a setup to get the printer connected to your wireless network, then the printer that exists on your Mac is for USB connections only. Thus, when you disconnect the printer USB from the Mac but try to print to this printer, it will show an offline message. The fix is to remove this USB printer from Print & Scan and adding the network connected printer to the Mac.

Having same problem with Epson 310. Ipad can print but Mac is giving me a printer offline message when I try to print I followed your steps now the Mac can print but the Ipad can't