c# - Spawning a Sphere and trying to move it

I've been trying to build upon a blog post on Gamasutra http://www.gamasutra.com/blogs/DarrelCusey/20130221/187128/Unity_Networking_Sample_Using_One_NetworkView.php In this I would like to spawn a sphere on the server and move it about and when it moves have the movement sent to the clients. On the GUI on the server I just want 3 buttons, spawn sphere, move left and move right. Ive been able to get the sphere to spawn fine, but when I press the button to have it move left or right nothing happens. Have I thought about this too simply? Where have I went wrong or what have I not included?

//***New Code***
        if(GUILayout.Button ("Spawn sphere"))
        {
            Instantiate(spawnedSphere);
            Debug.Log("sphere spawned");
        }
        if(GUILayout.Button ("Move Sphere Left"))
        {
            spawnedSphere.rigidbody.AddForce(new Vector3(-5000, 0, 0));

            Debug.Log("Sphere went left");
        }
        if(GUILayout.Button ("Move Sphere Right"))
        {
            spawnedSphere.rigidbody.AddForce(new Vector3(5000, 0, 0));
            Debug.Log("Sphere went right");
        }

        //***End New Code***

Answer

Replacing "Instaniate(spawnedSphere)" on line 3 with "spawnedSphere = GameObject.Instantiate(spawnedSphere) as GameObject;" fixed the problem.

After instantiating spawnedSphere, I didn't change its value. So I was trying to add force to the prefab.