broken menu button

i have a button script that used to work on a previous game i’ve made, but it doesnt work now. what is wrong with it?

heres the script, its C#

using UnityEngine;
using System.Collections;
 
public class Button1 : MonoBehaviour 
{
 
    public bool isQuit = false;
 
    void OnMouseEnter()
    {
       renderer.material.color = Color.blue; 
    }
 
    void OnMouseExit()
    {
       renderer.material.color = Color.white;
    }
 
    void OnMouseDown()
    {
       if(isQuit)
       {
         Application.Quit();  
       }
       else
       {
         Application.LoadLevel("1"); //Make sure that level "1" is located in your build settings. You can also change the 1 with a name of your scene.
 
       }
    }
}

Check that you have a scene named 1, but what I think is that you are trying to load the Scene file at index 1, which is written without quotation marks.

What you are implying:

Application.LoadLevel("1"); //Load 1.unity

What I think you mean:

Application.LoadLevel(1); //Load the 2nd scene in Build Settings