Hmm. I don't know then. Is it a USB 2 or 3 port? a USB 1.0 port might potentially not have enough current. It's designed for USB 2 but seems to work on USB 3 no problem. Do you get an error on your PC. If it says something like this device is can't be recognized. Sometimes the USB port shorted out by plugging in while power was turned on and you have to completely disconnect power to the computer. Not just shut down but pull out the power cable on a desktop or physically disconnect the batterty on a laptop which resets the motherboard. There's a utility called USBDeview for the PC that lets you troubleshoot and deactivate and reenable USB ports and devices. That might work without disconnecting the power. Oh. Make sure you try a different USB port first though. They shouldn't all have problems. If none of the above works I'm not sure what to suggest. It might end up being the USB on the amp thats the problem. You could try a factory reset and unplug it just to see if the USB socket on the amp needed to be reset. That's all I can think of and I'm not sure if you have a mac.