Ground bleeds through parking ramp

I'm having trouble with the ground bleed through my parking ramps at an airport that I've built for fs9 using AFCAD2.
The ramp appears to be somewhat transparent like tissue paper when viewed from above or flying over the airport. All other areas look ok.
I've used the flatten and exclude switches and that is ok, except that at night the lights of excluded houses and buildings bleed through the ramps.
This doesn't happen if I set the ramp to tarmac texture, I'm using the concrete texture.
Does anyone have any ideas
The ramp appears to be somewhat transparent like tissue paper when viewed from above or flying over the airport. All other areas look ok.
I've used the flatten and exclude switches and that is ok, except that at night the lights of excluded houses and buildings bleed through the ramps.
This doesn't happen if I set the ramp to tarmac texture, I'm using the concrete texture.
Does anyone have any ideas
