1. Check that both devices are turned on and that the correct cables have been connected correctly
2. Check to make sure the Input Settings are set up to recognize the cable box properly
3. Make sure all other devices are not connected and that your Smart TV is the only device connected connected via the HDMI ports
4. Reset the cable box and try re-pairing it with your Smart TV
5. Reset your Smart TV and try again
6. Contact your cable provider for troubleshooting information