Instantiated bullet wont destroy

Hello, I have a strange problem. My prefab should be destroyed when touching an Enemy. It is OK when I drag my prefab from Assets to Hierarchy and start a game. But when i instantiate this prefab during the game from another script it is not destroying.

Prefab consists of empty game object and 2 child objects inside (2 bullets). Script on this prefab is like this:

private void OnTriggerEnter2D(Collider2D collision) {

     if (collision.gameObject.tag == "Enemy")
     {
         FX();
         collision.GetComponent<EnemyBehaviour>().ReceiveDamage();
         Destroy(gameObject);
                 }

}

FX() is starting fine Damage is fine but the last step wont work.