fix issue 449
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/GetItemDescriptor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/GetItemDescriptor.java
index b41347d..c30fb6d 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/GetItemDescriptor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/GetItemDescriptor.java
@@ -109,7 +109,7 @@
                         }
                         if (itemIndex < 0)
                             throw new AlgebricksException(AsterixBuiltinFunctions.GET_ITEM.getName()
-                                    + ": item index can be negative!");
+                                    + ": item index cannot be negative!");
 
                         itemTag = EnumDeserializer.ATYPETAGDESERIALIZER.deserialize(serOrderedList[1]);
                         if (itemTag == ATypeTag.ANY)