dispatchKeyEvent does not trigger in Unity - Native Android plugin

I'm trying to detect the Volume UP or Volume down button press on an Android device(allow a "selfie stick" to control the phone). I created a plugin using this tutorial.

http://addcomponent.com/android-native-plugin-unity/

While the function "whatsThePoint" does return a value to a Unity c# script, I can't get the dispatchKeyEvent function to trigger - when I hit the volume up/volume down buttons on the device. (I looked at Android monitor/logcat in Android Studio)

Is there something I'm missing?
here is my .java code

Code (CSharp):

1. package com.addcomponent.unitynativeplugin;
2. import android.util.Log;
3. import com.unity3d.player.UnityPlayer;
4. import android.view.KeyEvent;
5. import  android.app.Activity;
6.  
7. public class Examples extends  Activity{
8.  
9.  
10.     public void whatsThePoint(String gameObject, String method) {
11.        
12.         UnityPlayer.UnitySendMessage(gameObject, method, "good.");
13.     }
14.    
15.    
16.     @Override
17.     public boolean dispatchKeyEvent(KeyEvent event) {
18.  
19.         int action = event.getAction();
20.         int keyCode = event.getKeyCode();
21.         switch (keyCode) {
22.             case KeyEvent.KEYCODE_VOLUME_UP:
23.                 if (action == KeyEvent.ACTION_DOWN) {
24.                     Log.d("test", "Volume UP pressed! " + event);
25.                     UnityPlayer.UnitySendMessage("NativeBridge", "WhatsThePointReceived", "VOLUME up");
26.                 }
27.                 return true;
28.             case KeyEvent.KEYCODE_VOLUME_DOWN:
29.                 if (action == KeyEvent.ACTION_DOWN) {
30.                     Log.d("test", "Volume DOWN pressed! " + event);
31.                     UnityPlayer.UnitySendMessage("NativeBridge", "WhatsThePointReceived", "VOLUME down");
32.                 }
33.                 return true;
34.             default:
35.                 return super.dispatchKeyEvent(event);
36.         }
37.     }
38. }

Here is the C# code that receives the data from the plugin

Code (CSharp):

1. public void WhatsThePointReceived (string message)
2.     {
3.         appMessage = message+"::"+Time.fixedTime;
4.     }