title: Unity & Vuforia: Implementing ITrackableEventHandler Interface is not being called
body: <p>I'm creating an AR app using Unity and Vuforia. I am trying to customize the behavior that objects have when found, and I am having trouble.</p>
  
  <p>I am implementing the ITrackableEventHandler interface within my class, however, this is not being called when running.</p>
  
  <p>I have thrown some simple Debug.Logs in order to check if these functions are being called and nothing is.</p>
  
  <p>-What I've Tried -</p>
  
  <p>I'm under the assumption that I need to apply this script on the ImageTarget itself, but I may be wrong.</p>
  
  <p>I've tried both keeping and removing the Default Trackable Event Handler script, and I still have had no success.</p>
  
  <p>Is there a piece I'm missing regarding what to implement or how I implement the interface?</p>