Video may not be calibrated properly. See Section 3.3 – “Calibrating the Subject Video Display”.
Docking station calibration was not performed. Recalibrate the subject.
Subject and KINARM robot/chair were moved since last time docking station calibration was performed. Recalibrate the subject.
Virtual plane not aligned with plane of movement. See Section 2.7 – “Setting up 2D Virtual Reality”. If the virtual plane is adjusted to correct an error, then the video calibration will need to be retested (and possibly recalibrated) and the subject will need to be recalibrated.