Changing the cubes colour over the network

I have a cube already in the scene with a network identity on it i have not got anything tick in its propities.
I want to have the player come to it and press e to change the colour on it. Is this the correct way cause its not working.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.Networking;
5. using UnityEngine.UI;
6.  
7. public class ColourChangingCube : NetworkBehaviour {
8.  
9.   private NetworkIdentity playerIdentity = null;
10.   public bool isTriggered = false;
11.   public Text interactText;
12.  
13.   private Renderer cubeRenderer;
14.  
15.   void Awake()
16.   {
17.     GetComponent<Renderer>();
18.   }
19.  
20.   void OnTriggerEnter(Collider collider)
21.   {
22.  
23.     ///check that is is a player
24.     if(collider.gameObject.tag == "Player")
25.     {
26.       isTriggered = true;
27.     }
28.   }
29.  
30.   void Update()
31.   {
32.     if(isTriggered)
33.     {
34.       interactText.enabled = true;
35.       if(Input.GetKeyDown(KeyCode.E))
36.       {
37.         CmdChangeCubeColour();
38.         print("triggered");
39.       }
40.  
41.     }
42.     else
43.     {
44.       interactText.enabled = false;
45.     }
46.   }
47.  
48.   void OnTriggerExit(Collider collider)
49.   {
50.     if(collider.gameObject.tag == "Player")
51.     {
52.       isTriggered = false;
53.     }
54.   }
55.  
56.  
57.   [Command]
58.   void CmdChangeCubeColour()
59.   {
60.     RpcColourUpdate(this.gameObject);
61.   }
62.  
63.   [ClientRpc]
64.   void RpcColourUpdate(GameObject go)
65.   {
66.     cubeRenderer = go.GetComponent<Renderer>();
67.  
68.     print("called");
69.     if(cubeRenderer.material.color == Color.white)
70.     {
71.       print("turn green");
72.       cubeRenderer.material.color = Color.green;
73.     }
74.     else
75.     {
76.       print("turn white");
77.       cubeRenderer.material.color = Color.white;
78.     }
79.   }
80.  
81.  
82. }