Creating a Flashing Color Script

I want to create a christmas lighting effect where the colors flash different colors I was thinking something like this yet I don't quite know...can anyone help?

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class FlashColorScript : MonoBehaviour
5. {
6.     public GUIText myText;
7.     public Color myTextColor;
8.  
9.     void Update ()
10.     {
11.         myText.material.color = myTextColor;
12.         StartCoroutine (Yield ());
13.     }
14.  
15.     IEnumerator Yield()
16.     {
17.         yield return new WaitForSeconds (1);
18.     }
19. }

 

Here is what it looks like done but when I assign the GUItext variable to the text it disappears :/

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class FlashColorScript : MonoBehaviour
5. {
6.     public GUIText myText;
7.     public Color myTextColor1;
8.     public Color myTextColor2;
9.  
10.     void Update ()
11.     {
12.         myText.material.color = myTextColor1;
13.         StartCoroutine (Yield ());
14.         myText.material.color = myTextColor2;
15.  
16.     }
17.  
18.     IEnumerator Yield()
19.     {
20.         yield return new WaitForSeconds (1);
21.     }
22. }