This means there is a connection error between your Smart Board and your Computer. 99% of the time this is due to either an unplugged USB cable which simply needs plugged back in or loss in communication at which point you can unplug the USB cable from your Computer and plug it back in to re-establish the connection. Once you see a green light, you have resolved the issue. If the issue persists, you are either missing the Smart Notebook Software, you have a bad USB cable or bad USB port, or your Smart Board has failed and the motherboard needs replaced at which point you would need to place a ticket for a technician to verify the issue and have it fixed.