Trying to swap scene when clicking a button

Hey guys,
I just simply want to swap scene when I click a button, atm I'm using the following script when attached to the button, however it's doing nothing.

using UnityEngine;
using System.Collections;

public class PlayGameButton : MonoBehaviour {
void OnMouseDown() {
Application.LoadLevel("Scene2");
}
}​

 

I've tried this too and it doesn't work

using UnityEngine;
using System.Collections;

public class PlayGameButton : MonoBehaviour {
if(Input.GetMouseButtonDown(0)){
Application.LoadLevel("Scene2");
}
}

 

Hey bud i found this to be usefull..

also remember you have to add your two scenes to (build settings)

 

Hey,
Firstly I appreciate the help Custard and it worked perfectly however it's not exactly what I wanted
I don't want to draw my own button using Unity's old GUI, I don't want a boring old box to click, as you can see from the screenshot I have made my own buttons "Play Game" and "Instructions" by using GameObject > UI > Button in the menu.
Is there a way I can attach some sort of script to a button in order for it to change scene?
Like anything similar to what I attempted?

Screenshot of Main Menu - http://i.imgur.com/prdbcKT.png


Edit: Do I use Button.onClick somehow?

 

Hey guys,
I got exactly what I wanted from this thread:

http://answers.unity3d.com/questions/836635/can-ui-buttons-load-scenes.html