Application.LoadLevel(""); - doesn't load my Scene

Hi, I want back to my menue when I lost my game, so when the time up. But timer disappears when the time is zero, so that works but it doesn't load my menue/scene.
Can anyone help me please :)

timer.js

 #pragma strict

 import UnityEngine.UI;
 
 var countdown : float;
 var timer : UI.Text; 
 
 function Start () {
   }

 function Update()
 {    
 timer = GetComponent(UI.Text);
 countdown -= Time.deltaTime;
  
 var minutes = Mathf.Floor(countdown/60).ToString("00");
 var seconds = (countdown % 60).ToString("00");
 timer.text = minutes +":" + seconds;
     if(countdown <= 0.00)
     { timer.active=false;
     Application.LoadLevel("Lostgame");
     
     }
 }