Check the following.
- Use the USB cable supplied with this unit.
- The USB cable is not connected properly to the USB port of the computer. Connect the USB cable again.
- Check that this unit and the computer are directly connected, not via a USB hub.
- A problem may occur with the connected USB port of the computer.
Connect to another USB port if it is available.
- Try the USB connection procedure again in cases other than those stated above.