 			try
 			{
 				this.xlsSheetsArray = xlsSheetsArray;
-				if (_attributeHierarchy.value == null)
+				if (_attributeHierarchy.value == null && xlsSheetsArray.length > 0)
 				{
 					// loop through column names, adding indicators to hierarchy
 					var firstRow:Array = xlsSheetsArray[0].values[0];

		{
		}
		
		override protected function initialize():void
		{
			super.initialize();

		private function getColumnValues(columnIndex:int):Vector.<String>
		{
			var values:Vector.<String> = new Vector.<String>();
			values.length = xlsSheetsArray[0].values.length - 1;
			for (var i:int = 0; i < values.length; i++)
			{
				if (columnIndex < 0)
					values[i] = String(i + 1);
				else
					values[i] = xlsSheetsArray[0].values[i + 1][columnIndex];
			}
			return values;
		}
		
