Please check the followings:
- Is the power cable of the scanner connected correctly and is the scanner switched ON?
- Use the USB cable which has been supplied with the scanner when you connect the scanner to computer. The scanner may become an unstable condition if you are using a commercially available cable or extended cable.
- Wait at least 5 seconds when you reconnect the power cable or open/close the cover. Without doing so, the scanner may not running properly.
- The scanner may not work if it is connected to the USB port on the keyboard or the monitor.
- Try to connect the scanner to other USB port.