Rotating my mesh towards other mesh

I have a problem rotating my mesh towards other mesh. my mesh is a cannon - it's face is where the cannons are going from. and i want it to rotate so it would face a cube. but it doesnt work. I tried everything.

Thank you for your help.

here is the relevant cannon script: (head is the part that should rotate)

  public float turningSpeed=5f;
     public Transform target; 
     public Transform head;
     private Quaternion rotation;
     
     
     // Update is called once per frame
     void Update () {
     
     if (target) {
     
     calcAimPosition (target.position);
     head.rotation = Quaternion.Lerp(head.rotation, rotation, Time.deltaTime * turningSpeed);
 } 
     }
     }
     public void OnTriggerEnter(Collider other)
     {
     if (other.gameObject.tag == "Enemy") { 
     target = other.gameObject.transform;
     }
     }
     public void OnTriggerExit(Collider other)
     {
     if (other.gameObject.transform == target)
     target = null;
     
     }
     public void calcAimPosition(Vector3 targetPos)
     {
  Vector3 aimPoint = new Vector3(targetPos.x -head.position.x, targetPos.y - head.position.y, targetPos.z - head.position.z);
     
     rotation = Quaternion.LookRotation (aimPoint-transform.position);
     
     }