InerfaceCast returns null for blueprint classes implementing that interface

Sorry if I was unclear, in my code lines 36 to 43 are commented out and they are the reason I reported this bug.
Lines 46 to 50 are the solution to the problem I had in lines 36 to 43.
This snippet is the event dispatcher part of my Kinect plugin.
The goal of this code is to make my plugin native code “free” so everyone could use it without the need to see native code.
To achieve that I created an Interface IKinectListenerInterface which can be implemented inside the editor by any class that the user wants to receive events from the Kinect.
While exposing native interfaces to blueprints is pretty much straight forward the other way using InterfaceCast method described here:

on an Blueprint generated class returns null.
I hope that explains my report better.