Crashing game after clicking on the login button "Google Play Services and Admob"

Hello,

I have a game that I inserted the google play services and admob plugins in, now everything works well, but when I click on the login button the game crashes! Below is the code:

Note that the game plays very good and the ads show up but when I click on the login button it crashes.

using UnityEngine;
using System.Collections;
using UnityEngine.SceneManagement;
using GooglePlayGames;
using GooglePlayGames.BasicApi;
using UnityEngine.SocialPlatforms;
// <copyright file="GPGSIds.cs" company="Google Inc.">
// Copyright (C) 2015 Google Inc. All Rights Reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//    limitations under the License.
// </copyright>
///
/// This file is automatically generated DO NOT EDIT!
///
/// These are the constants defined in the Play Games Console for Game Services
/// Resources.
///
public class LeaderScore : MonoBehaviour
{
        public const string achievement_5 = "******************"; // <GPGSID>
        public const string leaderboard_best_score = "******************"; // <GPGSID>
        public const string achievement_1 = "******************"; // <GPGSID>
        public const string achievement_2 = "******************"; // <GPGSID>
        public const string achievement_3 = "******************"; // <GPGSID>
        public const string achievement_4 = "******************"; // <GPGSID>
    public BirdMovement playerScript6;
    private static int MyScore;
    // Use this for initialization
    void Start()
    {
        PlayGamesPlatform.Activate();
        MyScore = Score.highScore;
        //PlayGamesPlatform.DebugLogEnabled = true;
        GetComponent<Canvas>().enabled = false;
    }
    // Update is called once per frame
    void Update()
    {
        if (playerScript6.dead)
        {
            GetComponent<Canvas>().enabled = true;
            Social.ReportScore(MyScore, "***************", (bool success) => {
                if (success)
                {
                    Debug.Log("You've Successfully Logged In");
                }
                else
                {
                    Debug.Log("Login Failed");
                }
            });
        }
    }
    public void LoadLeaderUI(int level)
    {
        //Application.LoadLevel(Application.loadedLevel);
        //PlayGamesPlatform.Instance.ShowLeaderboardUI("CgkIrsDSzs4HEAIQBg");
        Social.localUser.Authenticate((bool success) =>
        {
            if (success)
            {
                Debug.Log("You've Successfully Logged In");
            }
            else
            {
                Debug.Log("Login Failed");
            }
        });
    }
}

Hello guys,
Any help?

I’m also having the same problem. It doesn’t call the callback function!