Unity Game Over Screen Not appearing when player hits objects.

Hi.. I am new to Unity. I am currently making Google Dino Game in Unity. I have almost finished it but i got a problem. My Game Over Screen is not appearing when the dino hit the cactus.

This is my code:

using UnityEngine;

public class PlayerCollision : MonoBehaviour
{
    public GameObject gameOverScreen;
    public Rigidbody2D body;

    void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.transform.tag == "Enemy")
        {
            gameOverScreen.SetActive(true);
            body.velocity = Vector2.zero;
        }
    }
}

Do i need to write more code or something? Pls help me.

Thx in advance!