night textures - transparent

Before anyone scolds me, I have researched this topic but can't seem to find exact issue I'm experiencing. I purchased a bunch of blue print simulation airports. they're really good. But the nightime window twxtures really need help. So used dxtb (or whatever it's called) to edit other nightime window photos into the blue print _lm textures. It works, they look more like real nightime airport windows, but it makes the airport buildings transparent. Any way to prevent this. I read that you add a solid black texture and name it the same as the t_bmp texture, but I alreaady am changing the night texture that comes with it.