 		{
 			_changed = new Signal('VertexStream.changed');
 			_boundsChanged = new Signal('VertexStream.boundsChanged');
+			_minimum = new <Number>[];
+			_maximum = new <Number>[];
 			
 			_resource = new VertexBuffer3DResource(this);
 			_format = format || DEFAULT_FORMAT;

		{
			_data.position = _data.bytesAvailable;
			_data.writeFloat(value);
			_data.position = 0;
			
			if (!_locked)

			
			var boundsHaveChanged : Boolean = false;
			
			if (offset >= _minimum.length || value < _minimum[offset])
			{
				_minimum[offset] = value;
				boundsHaveChanged = true;
			}
			else if (offset >= _maximum.length || value > _maximum[offset])
			{
				_maximum[offset] = value;
				boundsHaveChanged = true;
