FlashDevelop: getDefinitionByName ReferenceError: Error #1065: Variable ... is not defined.

When I was using getDefinitionByName to create dynamic class.
var myClass:Class = getDefinitionByName('Item1') as Class;

I usually got this error:
[Fault] exception, information=ReferenceError: Error #1065: Variable Item1 is not defined.

Fixed: just including complete library
assets.swf -> Add To Library -> Options -> Included library(include completely)

[ref]
http://www.flashdevelop.org/community/viewtopic.php?p=27575