Why has my Dirt apron the Default material assigned ?

[TheEagle]

I am making a custom landing strip for the Wednesday Evening Event. In WorldEditor, I assigned the Dirt material to both the runway and the apron. But when I generate the airport with TerraGear, fly there with the UFO, the runway looks like sand / dirt, as it should, but the apron looks like rock:



When I Ctrl+Alt+Click on the runway, it shows up as dirt_rwy, but when I Ctrl+Alt+Click on the apron, the UFO tells me that the apron has the Default material assigned ? Firstly, how could this happen ? How am I supposed to change the apron texture ? If I would assign a new texture to the Default material, that texture would show up on all Default areas.

At other airport, the taxiway and aprons show up as "pa_tiedown" or suchlike. How do I change my apron material ? Please help !