Grid boxess rendering odd in AC

I'm working on a track; my first. The start lines (grid boxes) are rendering quite odd in AC; you can see in the in-game photo that the grid boxes render as a dark black shiny patch along the front straight, i.e. consistent with the dimensions of the grid box plane-object.
Even more strange is that those same grid boxes render just fine in KS Editor (second photo), i.e. the grid boxes are clearly visible and there's none of the "shimmering black" surface seen in AC.
The material shader settings are seen in the second photo.

Any help greatly appreciated.

 

Did you set the object/mesh in ksEditor to transparent?

 

Do you mean where it says "Is Transparent" that I should select [True]?

 

Exactly.

 

thanks. so much to learn. I'll try that. I thought as ksperpixelAlpha it'd already be transparent