To comment on the lighting changes. Sunlight is one of the types of light that will shift the reflected green colors more than almost anything else. Also, while light bulbs are produced to certain standards, sunlight has no such standards and can vary widely depending on mother nature's mood.
The effect of the sunlight that causes problems isn't the brightness of the sun, but the color. Commonly being yellow, it will shift the green up and the pink down.
As Alan mentioned, we attempted to make the HSL threshold wide enough to work in most environments, but understanding it and learning to predict and control the camera is of course a really good thing. To assist with this, a new white paper is up.
http://phoenix.ni.com/support/softli...hitepaper.docx