I'm having difficulty understanding how the supplemental light works on my Colorvu (DS-2CD2347G1-L and DS-2CD2T47G1-L) cameras. I've tried to improve the image quality by reducing the gain of the camera. However, for some reason now the supplemental light will no longer turn on automatically) when it gets dark. If I increase gain again, the light will turn on. Can anyone give me an idea of how this is supposed to work? Thanks