Are the USB port and plug both clean? Sometimes dirt/dust buildup, etc., can keep things from connecting cleanly, and cause an error to come up. According to my far more tech-savvy dad, sometimes the packaging process includes a protective film over the contacts that needs to be thoroughly wiped off, too.
My laptop has an external disk drive, and I have the option to connect it to the wall for power and then to the computer via USB, or to connect it with this funky combo-cable that is a USB plug with an additional pin mounted next to it to draw power from the laptop battery. The combo-cable gives me the same problem, and I almost never use it.
About the only real fix I've found is to unplug it, blow out the plug, wipe the contacts with a soft cloth, and try again. Sometimes it takes a few attempts, but I can always eventually get it to connect that way.