Check and make sure the floor where the scale is being used is level. If scale is still reading incorrectly, it may be out of calibration. To double-check take a known weight and place it on the scale to see what it is reading. If the scale is not within tolerance, the scale may need to be calibrated. If your scale will not zero out make sure no one is on the scale and nothing is touching the scale. Manually zero unit out by pressing the zero key and try weighing the patient again. If problem still exists contact Technical Support for further assistance at 1 (800) 638-3722.