Okay, so you renamed the file in GMax, but......did you rename the file in your a/c's ..\texture folder?

Yes that was it also, so here is the recap.At night, Self-Illumination under Preview X10, requires a valid .bmp file, else the FSX splash screen will be used.For experimental aircraft that should not be flying at night, using a black image, with black alpha channel in the .bmp, allows the panel light to light the gauges dimly, reminding one they should not be flying at night.Thanks for the help

I'm glad you finally got it all sorted out. Now you will remember the solution better! ;)