SerializationException: End of Stream encountered before parsing was completed.

When I try to save and load this error shows. I tried to delete "playerEdu" line and its work great. I think "int" and "string" doesnt work together. Any idea?

 using UnityEngine;
 using System.IO;
 using System.Runtime.Serialization;
 using System.Runtime.Serialization.Formatters.Binary;
 
 
 public class SaveLoadSystem
 {
     public static void Save()
     {
         BinaryFormatter bf = new BinaryFormatter();
         string path = Application.persistentDataPath + "/player.bin";
         using (FileStream fs = new FileStream(path, FileMode.Create, FileAccess.Write))
         {
             bf.Serialize(fs, SaveData.playerMoney);
             bf.Serialize(fs, SaveData.playerBankMoney);
             bf.Serialize(fs, SaveData.playerHealth);
             bf.Serialize(fs, SaveData.playerHunger);
             bf.Serialize(fs, SaveData.playerDay);
             bf.Serialize(fs, SaveData.playerYear);
 
             bf.Serialize(fs, SaveData.playerEdu);          
 
             fs.Close();
         }       
     }
 
     public static void Load()
     {
         if (!File.Exists("/player.bin"))
             return;
 
         BinaryFormatter bf = new BinaryFormatter();
         string path = Application.persistentDataPath + "/player.bin";
         using (FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read))
         {
             SaveData.playerMoney = (int)bf.Deserialize(fs);
             SaveData.playerBankMoney = (int)bf.Deserialize(fs);
             SaveData.playerHealth = (int)bf.Deserialize(fs);
             SaveData.playerHunger = (int)bf.Deserialize(fs);
             SaveData.playerDay = (int)bf.Deserialize(fs);
             SaveData.playerYear = (int)bf.Deserialize(fs);
 
             SaveData.playerEdu = (string)bf.Deserialize(fs);       
 
             fs.Close();
         }
     }
 }
 
 [System.Serializable]
 public class SaveData
 {
     public static int playerMoney;
     public static int playerBankMoney;
     public static int playerHealth;
     public static int playerHunger;
     public static int playerDay;
     public static int playerYear;
     public static string playerEdu;
 }