Touch and Drag for Android problem

I am working on 2d using orthello.

I have an object called as 'Wall' in the hierarchy and have attached this script 'Wall.cs'.

Below the wall is a 'background' object.

The code drags the background while the wall does not move at all. Isn't the keyword 'this' a reference to the wall instance since the class is a 'Wall'?

 using UnityEngine;
 using System.Collections;
 
 public class Wall : MonoBehaviour {
     
     void Update () {
         int speed = 100;
 
         if (Input.touches.Length > 0) {
             // Only work with the first touch
             // and only if the touch moved since last update
             if (Input.touches[0].phase == TouchPhase.Moved)
             {
                 float x = Input.touches[0].deltaPosition.x * speed * Time.deltaTime;
                 float y = Input.touches[0].deltaPosition.y * speed * Time.deltaTime;
                 this.transform.Translate(new Vector3(x, y, 0));
             }
         }
 
     }
 }