Problem with Load Level Script

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class uiManager1 : MonoBehaviour {
public Button buttons;
public Text scoreText;
bool gameOver;
int score;

// Use this for initialization
void Start() {
gameOver = false;
score = 0;
InvokeRepeating ("scoreUpdate", 1.0f, 0.5f);
}


// Update is called once per frame
void Update() {
	scoreText.text = "Score: " + score;
}

void scoreUpdate(){

	if (gameOver == false) {
		score += 1;
	}
	//if (score != 20) {
	//	Application.LoadLevel ("Level1");
	//} 
	if (score == 10) {
		Application.LoadLevel ("Level2");
		//if (gameOver != false) {
	}

		if(score == 11){
			Application.LoadLevel ("Level3");
			}
		 }

public void play(){
	 
		Application.LoadLevel ("Level1");
	 
}

public void gameOverActivated(){
	gameOver = true;
	foreach (Button button in buttons) {
		button.gameObject.SetActive(true);
	}
}

public void pause(){
	if (Time.timeScale == 1) {
		Time.timeScale = 0;
	
	} else if (Time.timeScale == 0) {
		Time.timeScale = 1;
		
	}
}
	public void Menu(){

		Application.LoadLevel ("menu");
	}

public void Exit(){
	Application.Quit ();
}

}

If you are using latest version of unity Applicaiton.LoadLevel will not work anymore.

Make a gameobject and attach this script

using UnityEngine.SceneManagement;

public void loadScene(string sceneName)

{

    SceneManager.LoadScene(sceneName);
}

In the Onclick() event of the button, drag the script77206-screenshot-3.jpg Note: The name must be exact same to the scene name.