Here's the map fixed:
http://www.mediafire.com/?tnwazmlogiiThis is where you forgeted things
new InteriorInstance() {
position = "0 0 0";
rotation = "1 0 0 0";
scale = "1 1 1";
interiorFile = "~/Map_Slate/slate.dif";
useGLLighting = "0";
showTerrainInside = "0";
};
That was set to
interiorFile = "./Map_Slate/slate.dif";
Which trys to load onwards from the file rather then the games base directory. For example, it was trying to load "Add-ons/Map_Slate_Green/Map_Slate/slate.dif".
You also tried to load the map without a skybox, a big nono, you always need a skybox even if you turn it off.
materialList = "base/data/skies/Sky_Spooky1/resource.dml";
};
I also renamed the map so it appears as Stale Green rather then Slate_Green in the map list.