Can't change color of objects

This is a bit of code from my procedural building generation. I get a NullReferenceException for the two marked lines (37 & 38). I'm not using the default shader on the wall objects. Can anyone see what the problem might be?

Code (CSharp):

1. public class WallBehavior : MonoBehaviour {
2.  
3.     public Divider data;
4.  
5.     Renderer wallA;
6.     Renderer wallB;
7.  
8.     public void Start()
9.     {
10.         Renderer[] walls = GetComponentsInChildren<Renderer>();
11.         wallA = walls[0];
12.         wallB = walls[1];
13.     }
14.  
15.     public void Setup()
16.     {
17.         if(data == null)
18.         {
19.             return;
20.         }
21.  
22.         BuildingCell cellA;
23.         BuildingCell cellB;
24.         if(data.vertical)
25.         {
26.             cellA = data.cell1;
27.             cellB = data.cell2;
28.         }
29.         else
30.         {
31.             cellA = data.cell2;
32.             cellB = data.cell1;
33.         }
34.  
35.         Color colorA = GetColor(cellA);
36.         Color colorB = GetColor(cellB);
37.         wallA.material.color = colorA;//BUG HERE
38.         wallB.material.color = colorB;//BUG HERE
39.      
40.     }
41.  
42.     public Color GetColor(BuildingCell cell)
43.     {
44.         switch (cell.mainRegion.regionTag)
45.         {
46.             case "OUTDOORS":
47.                 return Color.grey;
48.             case "BATHROOM":
49.                 return Color.cyan;
50.             case "BEDROOM":
51.                 return Color.red;
52.             case "BEDROOM1":
53.                 return Color.green;
54.             case "HALLWAY":
55.                 return Color.yellow;
56.             case "LIVING":
57.                 return Color.blue;
58.             case "KITCHEN":
59.                 return Color.magenta;
60.             case "DINING":
61.                 return Color.black;
62.         }
63.         return Color.clear;
64.     }
65. }

 

works for me.. try printing them out at Start and before assigning colors to see if they somehow are null,

Code (CSharp):

1. Debug.Log(wallA);
2. Debug.Log(wallB);
3.  

 

Okay, they work fine in start but return null before assigning colors. Thank you. Any idea what might cause something like this?

Edit: Problem resolved. Setup was being called before Start.