My Saving data when exiting app code does not work

public void OnExitAppDown()
{
BinaryFormatter bf = new BinaryFormatter();
FileStream file = File.Open(Application.persistentDataPath + "/playerInfo.dat", FileMode.Open);
PlayerData pdata = new PlayerData();
pdata.money = this.money;
pdata.moneyIncreasement = this.moneyIncreasement;
pdata.reviverCount = PlayerPrefs.GetInt("reviverCount");
pdata.reviverPercentage = PlayerPrefs.GetInt("reviverPercentage");
for (int i = 0; i < 4; ++i)
{
pdata.Bed = PlayerPrefs.GetInt("Bed" + i);
pdata.Reviver = PlayerPrefs.GetInt("Reviver" + i);
pdata.Sofa = this.Sofa;
pdata.Bookshelf = this.Bookshelf;
}
bf.Serialize(file, pdata);
file.Close();

Application.Quit();
}

this is the problem code.
this isn't a import problem, the code runs perfectly fine. but when I press the exitAppButton, It doesn't work... the game runs perfectly fine without exiting...
help me... I have to submit this app by tomorrow...

 

Don't use File.Open unless you change the FileMode to FileMode.OpenOrCreate. Use File.Create instead.