getDefinitionByName Problem

I am having trouble getting the getDefinitionByName method to work. I need to dynamically instanciate classes as part of a Quiz ( Question1, Question2, etc ).

private static const CLASS_PATH:String = "com.ea.application.view.questions.";
var _classRef:Class = getDefinitionByName( CLASS_PATH.concat( "Question", _num.toString() ) ) as Class;

ReferenceError: Error #1065: Variable Question1 is not defined.

There is no problem getting some of the other classes in the same folder so the paths are right.