Unable to save player data in a binary file within Update() method

Question

I'm trying to save player life within a binary file in Application.persistenceDataPath. I've written a method to store the player life:

  public void SaveLife()
     {
         BinaryFormatter bf = new BinaryFormatter ();
         FileStream file = File.Open (Application.persistentDataPath + "/playerInfo.dat", FileMode.Open);
         PlayerData data = new PlayerData ();
         data.savedLife = life;
         bf.Serialize (file, data);
         file.Close ();
     }

The problem is that when the SaveLife() is called OnApplicationQuit it works. Instead, if I call it within an Update() method of a class, it doesn't work.

The Update() method is called when a certain event is triggered:

void Update()
{
    if (life < 20)
    {
        if (//certain event is triggered)
        {
            SaveLife();
        }

        lifeTimer -= Time.deltaTime;
        if (lifeTimer <= 0)
        {
            ResetLife ();
        }
    }

}

The container class for the data is

[Serializable]
 class PlayerData
 {
     public int savedLife;
 }

What could be the problem?

Answer 1

The problem was caused by another SaveTime() method in the same script that was writing to the same file "playerInfo.dat".

public void SaveTime()
{
    BinaryFormatter bf = new BinaryFormatter ();
    FileStream file = File.Open (Application.persistentDataPath + "/playerInfo.dat", FileMode.Open);
    PlayerData data = new PlayerData ();
    data.savedTime = DateTime.Now;
    bf.Serialize (file, data);
    file.Close ();
}

Since in SaveTime() I was instantiating again Player data, this seems to cause the old Player data created by Update() to be substituted.

I solved the problem by instantiating Player date only once in the main body of the script.