1. Check that the scanner is properly aligned with your finger.
2. Make sure your finger is clean and dry.
3. Ensure that you are using a supported form of authentication with your device.
4. Try to restart the device to see if the problem goes away.
5. If the problem persists, it may be necessary to reset your settings or reinstall any apps or software that you may have recently installed.
6. If all else fails, you may need to contact the manufacturer's customer service for further assistance.