Reader sensor must be dry and clean. Both moisture and dirt can interfere with or prevent successful identification.
Finger was pressed on the sensor too lightly or too hard. It should be pressed with normal force.
The finger was placed on the sensor at an excessive angle. Place it parallel with the sensor.
Not enough finger surface was pressed on the sensor. The sensor must obtain a large enough image to enter the fingerprint. Please try again.
Database is full. A new fingerprint can be entered only after you delete one of the existing fingerprints.
Skin on the finger is very dry. Make sure you moisturize your hands.
To troubleshoot fingerprinting children, the elderly, and people with injured fingers, see "Storing Fingerprints" section.