Object Not Destroying?

I have a simple script setup to collect an object and destroy it. It's displaying it's text but not destroying the object. As well, it's giving me a Console message saying "Object reference not set to an instance of an object" and refers to line 47, which is where the line to destroy the object is. Any help??

 using UnityEngine;
 using System.Collections;
 
 public class Item : MonoBehaviour
 {
 
 
 
     ///////////////////////////////////////////////////////////////////////
     ///This file goes on a Collectable Game Object that is in your scene///
     ///////////////////////////////////////////////////////////////////////
 
 
 
     //Set up variables for text output on screen, and audio
     //This will create "open slots" in your editor, on the object that has this script
     //You will drop in your GuiText and Audio into the open slots.
     public GUIText TextOutput;
     public AudioClip SoundToPlay;
 
     //Set up variable for number of items collected.
     //Each time you collect something, this can be updated to be you "inventory" of that item.
     public static int itemCounter = 0;
 
     
 
     //Code for when the player collides with an item to collect.
     void OnTriggerEnter (Collider other)
     {
         //When something hits the collectable, if it is the player that touches the collectable,
         //Play a noise,
         //Display some text,
         //Update the inventory,
         //Delete the prefab.
         if (other.tag == "Player") {
             //Play the audio at the collectables position
             AudioSource.PlayClipAtPoint (SoundToPlay, this.transform.position);
 
             //Update the GuiText
             TextOutput.text = "You Collected An Item!";
 
             //Update the varible for the # of items you have in your inventory
             //The below code is a "shorthand" method of writing itemCounter = itemCounter +1;
             itemCounter += 1;
         
             //Simulate collection by destroying the prefab object
             Destroy (gameObject.transform.parent.gameObject);
         
         }
 
 
 
     }
 }