crash in standalone app not in editor

hey there, i've been making a game and it's almost finished. so i added a main menu and if i compile it into a standalone app (to test out the quit button) the app says powered by unity and then there's a black screen and then it crashes. this happens on mac and windows.

here is the start script that loads the level when pressed the start button

using UnityEngine; using System.Collections;

     public class Start: MonoBehaviour {
         public void LoadLevel(int Index = 1)
         {
         Application.LoadLevel(Index = 1);
         }
 }
  

and here's the quit script that quits the application when th quit button is pressed. using UnityEngine; using System.Collections;

 public class Quit : MonoBehaviour {
 
     public void ExitApplication()
     {
         ExitApplication();
     }
 }

i've tried application.quit but that gives the same result..... a crash

so this works in the editor but as a standalone application it crashes.

edit: i changed the start code it's this now and it still crashes

     using UnityEngine;
     using System.Collections;
     
     public class Start: MonoBehaviour {
     public void NextLevelButton()
         {
         Application.LoadLevel("game");
         }
 }