     # return if no request is needed
     return if @isBucketRequestedByZoomedAddress(address)
 
-    buckets = @cube[address[3]].buckets 
+    buckets = @cubes[address[3]].buckets 
     bucketIndex = @getBucketIndexByZoomedAddress(address)
 
     # mark the bucket as requested

  LOOKUP_DEPTH_UP : 0
  LOOKUP_DEPTH_DOWN : 1
  MAXIMUM_BUCKET_COUNT : 5000

  LOADING_PLACEHOLDER : {}

  cube : null
  upperBoundary : null
  access : null
  bucketCount : 0

    oldBucketLevel = bucket.level
    bucket.level = 0

    subCube = @cubes[zoomStep - 1]

    for dx in [0..1]
      for dy in [0..1]
