Make sure you don't have "use vertex colours" tuned on in the static mesh browser, and when you place the mesh set bDynamicLighting (or something) to false. Not sure what else it could be... bStaticLighting = true?
Also, make sure you put your combiner as the difuse material in a shadar material and use the shadar on your mesh not the combiner directly (apparently you have to do this though I never tried it without)
And make sure you didn't set a material for self-illumination or anything
Oh, and make sure you didn't set some stupid property like bUnlit to true