Facebook Invitable Friends profile picture

Hey, I am trying to get the Profile Picture of the Facebook friends of the user who are not yet playing the game. I have retrieved their usernames successfully and just stuck on getting the profile picture. here is the code I am using (I followed this tutorial here )

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 using Facebook.Unity;
 
 using System.Collections.Generic;
 
 
 public class FBLogin : MonoBehaviour {
 
     public GameObject login;
     public GameObject notLogin;
     public GameObject friend;
 
     void Awake()
     {
         if (!FB.IsInitialized) {
             FB.Init (InitCallBack);
         }
     }
 
     void InitCallBack()
     {
         print ("FB has Been Initialised");
     }
 
     public void Login()
     {
         if (!FB.IsLoggedIn) {
             FB.LogInWithReadPermissions(new List<string>{"user_friends"}, LoginCallBack);
         }
     }
 
      void LoginCallBack(ILoginResult result){
         if (result.Error == null) {
             Debug.Log ("Fb logged in!");
             login.SetActive (true);
             notLogin.SetActive (false);
             FB.API ("me/picture?width=100&height=100", HttpMethod.GET, PictureCallBack);
             FB.API ("me?fields=first_name", HttpMethod.GET, NameCallBack);
             FB.API ("me/invitable_friends", HttpMethod.GET, FriendCallBack);
 
         } else {
             login.SetActive (false);
             notLogin.SetActive(true);
         }
     }
 
     void PictureCallBack(IGraphResult result)
     {
         Texture2D image = result.Texture;
         login.transform.FindChild ("Image").GetComponent<Image> ().sprite = Sprite.Create (image, new Rect (0, 0, 100, 100), new Vector2 (.5f, .5f));
     }
 
     void NameCallBack(IGraphResult result)
     {
         IDictionary<string,object> profile = result.ResultDictionary;
 
         login.transform.GetChild (0).GetComponent<Text> ().text = "Hello, " + profile ["first_name"];
     }
     public void LogOut()
     {
         FB.LogOut ();
         login.SetActive (false);
         notLogin.SetActive (true);
 
     }
 
     public void Invite (){
         FB.AppRequest (message: "You Really should try this game.", title: "Covens");
     }
 
     public void Share(){
         FB.ShareLink (new System.Uri ("http://www.raincrowstudios.com/"), "This game is awesome!", "Discription about the game", new System.Uri ("http://www.raincrowstudios.com/images/covens_mast825.png"));
     }
     void FriendCallBack(IGraphResult result)
     {
         IDictionary<string, object> data = result.ResultDictionary;
         List<object> friends = (List<object>)data ["data"];
         foreach (object obj in friends) {
             Dictionary<string,object> dictio = (Dictionary<string,object>)obj;
             CreateFriend(dictio ["name"].ToString () , dictio ["id"].ToString());
         }
     }
 
     void CreateFriend(string name, string id){
         GameObject myFriend = Instantiate (friend);
         Transform parent = login.transform.FindChild("users");
         myFriend.transform.SetParent (parent);
         myFriend.transform.localScale = new Vector3 (1, 1, 1);
         myFriend.GetComponentInChildren<Text> ().text = name;
         FB.API ("me/invitable_friends/access_token="+id+"?fields=picture?width=100&height=100", HttpMethod.GET, delegate(IGraphResult result) {
             myFriend.GetComponent<Image> ().sprite = Sprite.Create (result.Texture, new Rect (0, 0, 100, 100), new Vector2 (.5f, .5f));
         });
 
 
     }
 }
 

I tried a bunch of ways to get the profile pictures none worked, I can't find the right syntax for it, would really appreciate it if someone can help me with this.

Thanks, Mridul