Can't add AddForce or velocity to RigidBody2D

Hello everyone, I’m trying to get the player knockback when touching an enemy. Everything works fine, but when I try to apply force to the player nothing happens. Does anyone know what the problem might be? Here is the code:

private void Start() 
  {
      Debug.Log(currentHealth);
      rb = GetComponent<Rigidbody2D>();
      playerMovement = GetComponent<PlayerMovement>();
      currentHealth = health;
      player = GameObject.Find("Player");
  }
  
 
  private void Update() 
 {

     if(rb.velocity.y < 0) {
         CheckAttackHitBox();
     }
     Debug.Log(currentHealth);
     if(rb.velocity.y >= 0 && playerStompedEnemy == false)
     {
          PlayerTouchEnemy();
     }
    
     if(touchDamageTime <= 0)
     {
         knockBack = false;
     }
     if(stompTime <=0)
     {
         playerStompedEnemy = false;
     }
 }
 
private void PlayerTouchEnemy()
 {
     enemyDetected = Physics2D.OverlapBox(playerPos.position, sizeOfBox, angle, whatIsDamageable);
     touchDamageTime -=Time.deltaTime;
     if(enemyDetected != null && touchDamageTime <= 0 )
     {
         
         attackDetails.damageAmount = attack1Damage;
         attackDetails.stunDamageAmount = stunAmount;
         gameObject.transform.SendMessage("Damage", attackDetails);
         rb.AddForce(knockBackDirection);
         knockBack = true;
         touchDamageTime = 1.5f;
         
     }
 }

Try to use rb.AddForce(knockBackDirection, ForceMode.Impulse); or rb.AddForce(knockBackDirection, ForceMode.Acceleration); and increase the force.