Void OnMouseDown not working in Prefab

Hi,

When I try to run the script with Void OnMouseDown attached to a GemaObject this works. When I instantiate the same object, OnMouseDown doesn't run.

Is there a solution to this problem?

Code (CSharp):

1.  
2. public class ActivateWhenClick : MonoBehaviour
3. {
4.     public GameObject Activate;
5.     private bool Show;
6.  
7.  
8.  
9.  
10.     public void OnMouseDown()
11.     {
12.         if(Show == true)
13.         {
14.             Activate.SetActive(true);
15.             Show = false;
16.         }
17.         else if (Show == false)
18.         {
19.             Activate.SetActive(false);
20.             Show = true;
21.         }
22.     }
23. }

Thanks in advance,

Louis