The way i read the manual, there is no "don't apply to sun" option. The sun is always included - the option is just to apply to sun + other lights or sun only.

This option works for me "as advertised" in GI lighting. For example: Both a sun and a spotlight on a white sphere, using the "black sky" atmosphere, sun is white color in sun "Light & Shadow" settings, but green in "Light Color" of GI settings, spotlight is white.

If set for "Apply setting to all lights, spotlighed area turns green - now all of scene is green. If "Sun Only", sun lighted area is green and spot lighted is white. If i turn off sun ("Influence" in "Light & Shadow") there is no sun, no green and only white spotlight illumination.

Maybe you are seeing some atmosphere effect that is simulating a sun effect whether the sun is on or not? That's why i used the black atmosphere. Have not tried this with other atmospheres.

_ jc...'Art Head Start' e-book
.......'Art Head Start.com site Digital Art skills. Free lighting chapter, tutes, Vue models, tex pix.