 				if (_stringToNumberFunction != null)
 					return Number(_stringToNumber[string]);
 				
-				return Number(_uniqueStringLookup[string]);
+				return Number(_uniqueStringLookup.get(string));
 			}
 			
 			if (dataType === IQualifiedKey)

		/**
		 * String -> index in sorted _uniqueStrings
		 */
		private var _uniqueStringLookup:Object;

		public function setRecords(keys:Array, stringData:Array):void
		{

				return false;
			
			// keep track of unique strings
			if (!_uniqueStringLookup.has(value))
			{
				_uniqueStrings.push(value);
				// initialize mapping
				_uniqueStringLookup.set(value, -1);
			}
			
			return true;
