How to access Vive controllers in a script attached on a simple game object(a cube)?

Hi all,

From an HTC Vive unity tutorial, I learnt the following way to access Vive controller from a script named ViveControllerInputTest and this script is attached to the Controller(left) and Controller(right) game objects. The snippet of code in ViveControllerInputTest is as shown below and I will explain my question after this snippet of code:

 private SteamVR_TrackedObject trackedObj;
 private SteamVR_Controller.Device Controller
 {
     get { return SteamVR_Controller.Input((int)trackedObj.index); }
 }
 void Awake()
 {
     trackedObj = GetComponent<SteamVR_TrackedObject>();
 }
 if (Controller.GetAxis() != Vector2.zero)
 {
     Debug.Log(gameObject.name + Controller.GetAxis());
 }
 if (Controller.GetHairTriggerDown())
 {
     Debug.Log(gameObject.name + " Trigger Press");
 }
 if (Controller.GetHairTriggerUp())
 {
     Debug.Log(gameObject.name + " Trigger Release");
 }
 if (Controller.GetPressDown(SteamVR_Controller.ButtonMask.Grip))
 {
     Debug.Log(gameObject.name + " Grip Press");
 }
 if (Controller.GetPressUp(SteamVR_Controller.ButtonMask.Grip))
 {
     Debug.Log(gameObject.name + " Grip Release");
 }

The code above is quite straightforward and it works very well. My question is, for now, I want to access my Vive controllers in a script attached on another simple game object(a cube) INSTEAD of Controller(left) and Controller(right) game objects themselves. And I have written my own code shown below but it doesn't work as normal(no errors but no Debug.Log print out in the console either). Can you please help?

 using System;
 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 namespace RosSharp.RosBridgeClient
 {
     public class TwistProvider : MessageProvider
     {
         GameObject viveObj;
         private SteamVR_TrackedObject trackedObj;
         private SteamVR_Controller.Device Controller
         {
             get { return SteamVR_Controller.Input((int)trackedObj.index); }
         }
 
         private float previousRealTime;
         private GeometryTwist message;
         private Vector3 previousPosition = Vector3.zero;
         private Quaternion previousRotation = Quaternion.identity;
         public override Type MessageType { get { return (typeof(GeometryTwist)); } }
         void Awake()
         {
             viveObj = GameObject.FindGameObjectWithTag("controller");
             trackedObj = viveObj.GetComponent<SteamVR_TrackedObject>();
         }
         public void FixedUpdate()
         {
             if (IsMessageRequested)
                 UpdateMessage();
             if (Controller.GetAxis() != Vector2.zero)
             {
                 Debug.Log(gameObject.name + Controller.GetAxis());
             }
             if (Controller.GetHairTriggerDown())
             {
                 Debug.Log(gameObject.name + " Trigger Press");
             }
             if (Controller.GetHairTriggerUp())
             {
                 Debug.Log(gameObject.name + " Trigger Release");
             }
             if (Controller.GetPressDown(SteamVR_Controller.ButtonMask.Grip))
             {
                 Debug.Log(gameObject.name + " Grip Press");
             }
             if (Controller.GetPressUp(SteamVR_Controller.ButtonMask.Grip))
             {
                 Debug.Log(gameObject.name + " Grip Release");
             }
         }