Physics.IgnoreCollision doesn't work, what is wrong with my code?

I tried Physics.IgnoreCollision with code but I don’t get what is wrong. I’m not so much experienced in C# and in Unity 3d.

I have a script that is attached on a gameobject (enemy) and in this script i create a bullet (preflab). My goal is that the enemy doesn’t block the bullet with himself.

        GameObject bullet = Instantiate(enemyShootBullet, shootingPoint.position, shootingPoint.rotation);
        Physics.IgnoreCollision(this.gameObject.transform.root.gameObject.transform.GetComponent<Collider>(), bullet.gameObject.transform.root.gameObject.transform.GetComponent<Collider>(), true);