Calibration error from CE-XTH

1. Ensure that the targeting foot is in the locked position.
2. Ensure that the white calibration tile is clean (no dust, dirt or fingerprints).
3. Ensure that the white tile aperture foot alignment notches match up with the aperture standard alignment ridge on the instrument and that the tile is locked in place and not held at an angle.
4. During open port calibration, ensure nothing is in front of the instrument for at least 5 feet. Do not point the instrument toward a glass surface, mirror or other surface that could reflect light back into the sphere.