Searching an ArrayList of Instanced Prefabs possible?

Hello everyone!. I have this little script that, with declarations and stuff ignored, SHOULD, change the color of a prefab, instance it, add it to an ArrayList and then print the colors of every object in the array list.
My problem is that, when I instance them and add them to the list, all is good, but when I search its colors, the instanced objects all gave NullReferenceExeption.

I was hoping someone could look at it and spot something im missing here.
Thanks in advance!

Code (csharp):

1.    
2.  
3. void Start () {
4.       timer = 0;
5.        ballList = new ArrayList();
6. }
7.  
8.      void Update () {
9.  
10.         timer += Time.deltaTime;
11.         if (ballList.Count < 10)
12.          {
13.             if (timer > 0.5)
14.             {
15.                 RandomizeColors(ballPrefab); //randomizes and assigns a material.
16.                 clone = Instantiate(ballPrefab, transform.position, transform.rotation) as GameObject;
17.               lista.Add(clone);
18.                 timer = 0;
19.             }
20.         }
21.         else
22.         {
23.             foreach (GameObject ballz in lista)
24.             {
25.                 Debug.Log(ballz.renderer.material.name); //NULL REFERENCE EXEPTION
26.                 //here goes the code that searches for balls of the same color and deletes
27.  them          
28.               }
29.         }
30.  
31.     }

 

SOLVED im dumb as a wall can be

 

Also why you using an ArrayList, a type array (ie GameObject[]) or a Generic List is better.