Does the cable come with a double USB connector on one end? If it does use both connector (one connector is just for added power). The reason its not working is because the USB port isn't providing enough power, this usually happens with front mounted USB ports on cheap cases (the cable for the front USB ports reduces the amount of power that reaches the actual port) and on some notebooks where the USB port is slightly underpowered to conserve battery. If its a desktop system you can try plugging it into the USB ports in the back.