Ошибка при передаче значения из другого класса

if (score > 2) 
        {
            ScreenSpeed=-5f;
        }

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;
 
public class GameControl : MonoBehaviour {
 
    public static GameControl instance;
    public GameObject gameOverText;
    public Text scoreText;
    public bool gameOver = false;
    public float scrollSpeed = -1.5f;
 
    public int score = 0;
 
    // Use this for initialization
    void Awake () 
    {
        if (instance == null) {
            instance = this;
        } else if (instance != this)
        {
            Destroy (gameObject);
        }
    }
    
    // Update is called once per frame
    void Update()
    {
        if (gameOver == true && Input.GetMouseButtonDown (0)) 
        {
            SceneManager.LoadScene (SceneManager.GetActiveScene ().buildIndex);
        }
    }
 
 
    public void BirdScored()
    {
        if (gameOver) 
        {
            return;
        }
        score++;
        scoreText.text = "Score: " + score.ToString ();
    }
 
 
    public void BirdDied()
    {
        gameOverText.SetActive (true);
        gameOver = true;
    }
 
    
 
 
    
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
 
public class ScrollingObject : MonoBehaviour {
 
    private Rigidbody2D rb2d;
 
    public float ScreeenSpeed = -2f;
    void Start () {
        
        rb2d = GetComponent<Rigidbody2D>();
        rb2d.velocity = new Vector2 (ScreeenSpeed, 0);
        //rb2d.velocity = new Vector2 (GameControl.instance.scrollSpeed, 0);
    }
    
    // Update is called once per frame
    void Update () 
    {
        if (GameControl.instance.gameOver == true) 
        {
            rb2d.velocity = Vector2.zero;
        }
 
 
        
        
    }
 
    
    
 
}

public static int score = 0; // 15 строка 1 кода
 
if (GameControl.score > 2) // в void Update ()

GameControl g = new GameControl();
if (g.score > 2)

void Start () {
        
        rb2d = GetComponent<Rigidbody2D>();
        rb2d.velocity = new Vector2 (ScreeenSpeed, 0);
        //rb2d.velocity = new Vector2 (GameControl.instance.scrollSpeed, 0);
    }

    if (GameControl.score >= 1)
        {
            ScreeenSpeed= -10f;
        }

rb2d.velocity = new Vector2 (ScreeenSpeed, 0);