Can't access other game object in build-ed version of the game but when testing in editor it works alright

So I have start button with code:

 GameControlScr gameControlScr;
     void Start () {
         gameControlScr = GameObject.Find ("GameControl").GetComponent<GameControlScr>();
     }
     
     void OnMouseDown()
     {
         gameControlScr.testMethod();
     }

When I test it from unity editor it works fine. It calls testMethod() and new scene is loaded. But when I build project into android or pc versions it won't call this method. It seems like it can't access gameControlScr. I also tried making gameControlSrc a static reference and it won't work as well. Btw testMethod() just have this line of code:

 public void testMethod(){
     Application.LoadLevel("Test01Level01");
 }