how to save and load game through unity Serializer

i want to save the game and load it on resumr button click.,so i used the link link.and i think with this i am able to save the game but unable to load it.,what am i doing wrong..??

 void Start () {
         if (MainMenu.Load == true) {
             //LevelSerializer.LoadSavedLevel(PlayerPrefs.GetString("AutosaveNameYouChoose"));
             foreach(var sg in LevelSerializer.SavedGames[LevelSerializer.PlayerName]) {
                 if(sg!=null){
                 if(sg.Level == "level01")
                 {
 
                         LevelSerializer.LoadNow(sg.Data);
                         //Time.timeScale = 1;
 
                 }
             } 
                 }
             //LevelSerializer.Resume();
         } 
         //Load ();
         if (MainMenu.New == true) {
 
 //do smothing here
 }
 
 public     void Save()
     {
         LevelSerializer.SaveGame(gamename);
         
     }

but i am getting error saveGameManager is null and board is null and

 MissingReferenceException: The object of type 'EmptyObjectIdentifier' has been destroyed but you are still trying to access it.
 Your script should either check if it is null or you should not destroy the object.
 UnityEngine.Component.SendMessage (System.String methodName, SendMessageOptions options) (at C:/BuildAgent/work/d3d49558e4d408f4/artifacts/EditorGenerated/UnityEngineComponent.cs:317)
 LevelLoader+<Load>c__Iterator8.MoveNext () (at Assets/Plugins/whydoidoit.com/Serialization/LevelLoader.cs:502)