There are no shadows on the lighter part of the apron. Here is a screenshot to show you what I mean.

As you can see, shadows appear on the darker surface, as well as the yellow taxi lines, but not on the lighter one. I am using P3Dv3 (have not installed 3.1 yet). I also have installed FTX Global, Vector and OpenLC Europe. Here is what my scenery library looks like, in case it's of any help.

Thanks in advance for your help.