You are missusing the singleton pattern.


The correct use would be this:

In `ScoreKeeper`

```lang-cs
public class ScoreKeeper : MonoBehaviour
{
    public static ScoreKeeper Instance { get; private set; }

    private void Awake()
    {
        if (Instance != null && Instance != this) // if we are the instance this is fine
        {
            Destroy(this);
            return;
        }

        Instance = this;
        DontDestroyOnLoad(this);
    }
}

```

Then when accessing it, don't hold on to a reference, just do this each time.

```lang-cs
ScoreKeeper.Instance.ResetScore();
```

Your error was occuring becuase `LevelManager`'s reference was somehow becoming null, likley because loading into the game made the original `ScoreKeeper` delete itself due to the error in it's awake logic