Changed Prefab tag Still objects untagged??

I created prefab and tagged it with "Player" .But the clone objects they still untagged i even printed void OnCollisionEnter2D(Collision2D collInfo){ Debug.Log (collInfo.collider.tag); //Prints untagged if(collInfo.collider.tag=="Player") Debug.Log("CAlled"); } I cant understand why this is happening ? I changed the prefab tag ,still its clones are untagged