How to enhance managed bean?

Dear experts,

I try to enhance custom module by redirect managed bean class from standard pointing to my custom class. I don't change managed-bean-name but just change managed-bean-class to my custom class. After deploy and run, it still use the bean still use standard class not mine. Any ideas why it still runs the standard?

Moreover, if I try to change the managed-bean-name, it will error. Why?

PS: I already use @WCFScope(scope = WCFScope.Scope.VIEW) in my custom class which will be used view.

Regards,

Daro