Gail,
You will want to check that the USB cable from the computer to the board is connected and secured. Please ensure that you have a direct 16ft USB connection and there are no USB extensions or boosters attached. If you are connected to a wallbox or connectivity panel, try and bypass it and connect directly to the board. If this does not resolve the issue please contact Technical Support via the web form on the knowledge base at ww.prometheankb.com, select your region/language, Interactive Displays, Contact Us. In the Existing case field input case number: 256091. Please also provide the serial number for the board.
Thanks!