Rotate One Object Around Another

Hello, this has been bothering me really bad for the past hour and i still cant figure it out. Im trying to get one Sphere to rotate around another Sphere. This is my code:

using UnityEngine;
using System.Collections;

public class Shooting : MonoBehaviour {

public Transform player;

void Update () {
        transform.RotateAround (player.position, Vector3.up, 20 * Time.deltaTime);
    }

}

Ive tried so many things to try to get this to work and there has been absolutely no progress, also to be quiet honest i usually dont have these kind of simple problems haha.

Thanks for the help

Maybe this will help