Can't access Array in a class instance multidimensional Array.

I have a Multidimensional Array

 var cubes: VoxCube[,,];

I set it

 function Awake () {
     cubes = new VoxCube[l,w,h];
 }

I then have a function to fill out all of the data in the VoxCube[,,]

 function BaseChunk() {
     for(var x=0; x < l; x++){
         for(var y=0; y < w; y++){
             for(var z=0; z < h; z++){
                 
                 var isVisible: boolean = false;
                 var isMeshVect: int = 0; // 0 not used 1 used
                 var isGround: boolean = false;
                 
                 if(y == groundOffset){
                     isGround = true;
                     isMeshVect = 1;
                     isVisible = true;
                 }
                 
                 //init location

                 cubes[x,y,z] = new VoxCube();

                 var voxLoc: VoxCube = cubes[x,y,z] as VoxCube;
                 voxLoc.visible = isVisible;
                 voxLoc.origin = Vector3(x,y,z);
                 //setup ghost vertices
 ERROR: null----> voxLoc.ghostVertices[0] = Vector4(x*s,y*s,z*s,isMeshVect); //0,0,0 

VoxCube is this

 class VoxCube extends Object
 {
     public var visible: boolean;
     
     public var origin: Vector3; //point location in VoxLevel
     
     //The basic locations of the 8 Verticies:
     public var ghostVertices: Array;
     
     public var textureIds: Array;//MAX 6 one cube for each side.
     
     public var exportedVertices: Array;
     public var exportedTriangles: Array;
     public var exportedUV: Array;
     
 }

It keeps telling me voxLoc at the first ghostVertices line is a Null Reference Exception. I don't get why voxLoc moments before is fine but as soon as I try to put anything into that array within the VoxCube class it barfs on me. I'm sure it's something simple I'm missing. Any advice is welcome.