Having troube with getTerrainMapIndex.

I seem to be having some trouble when getting a color I've assigned to a texture via the material property map. I have code inside the "missionAreaEditor.cc" file that covers a portion of the missionArea map with pixels.

Now I'm trying to use the following code segment to color the pixels with a color that I've assigned to texture below the pixels.

Point3F pixel3F;
   Point2F pixel2F = screenToWorld(Point2F(posX, posY));
   pixel3F.set(pixel2F.x, pixel2F.y, 0);

   S32 mapIndex = terrain->getTerrainMapIndex(pixel3F);
   MaterialPropertyMap* pMatMap = static_cast<MaterialPropertyMap*>(Sim::findObject("MaterialPropertyMap"));
   const MaterialPropertyMap::MapEntry* pEntry = pMatMap->getMapEntryFromIndex(mapIndex);

   glColor3f(pEntry->groundColor.red, pEntry->groundColor.green, pEntry->groundColor.blue);
   glVertex2f(posX, posY);

I believe my problem dwells within this bit of code because of several tests. In "materialPropertyMap.cc", I have groundColor initialized to black. However, when I manually change it to something like red or blue, the drawn pixels are still black. So I believe either mapIndex, pMatMap, or pEntry are not getting there correct values. I'm gonna do some more testing to try and find which one.

Anyways, I get no errors when I compile, and I can't see any obvious reason for this not to work.
Thanks for any help.