Printer setup error: Unable to communicate with the printer

I have a brand new 24" iMac. Bought a new HP ENVY 6055. Setup went smoothly until the very end. Could select, but not add printer. HP Technical Support could not help, and suggested getting a replacement printer. I took back the HP and got a Brother inkjet instead. Same thing happened. I have an Apple Extender to increase the range of my internet--could this have anything to do with the problem? Can I use a USB cable instead of AirPrint? (I have an Anker adapter).