Lighting Changed
The illumination of the markings has changed since they were detected, prior to straining. Can be caused by something blocking light from Vector to the specimen, or changes in lighting from another source.
Solutions
Prevent any partial obstructions of the Vector lights.
Check that no obstructions occur from the operator during specimen mounting, such as a hand infront of the lights.
Shield the test area from changing daylight.
Block out daylight by closing window blinds. Daylight can fluctuate during specimen mounting.
Ensure that other light sources do not shine on the test area.
Check for nearby bright lights being turned on or off.
Information

After moving the module or specimen, wait a few seconds for warning indicators to settle.