SpriteRenderer.sprite change from Sprite array is not working

Please help me to made this script work.
The SpriteRenderer get component does not work

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class mapTypeScript : MonoBehaviour
{

public mapEventType mapEventType;

// Ihave put the  15 sprite on the array...
public Sprite[] mapTypeSprites = new Sprite[15];

private Sprite SpriteRendererRoof;


// Use this for initialization
void Start()
{

    //This is not working
    SpriteRendererRoof = this.transform.parent.GetChild(0).GetComponent<SpriteRenderer>().sprite as Sprite;

    if(SpriteRendererRoof == !null)
        {

            Debug.Log("This is work");
         }
    // this is not working too
   SpriteRendererRoof = mapTypeSprites[5];
}

}

My component targeting was not good : problem solved