I need help with making a pause menu.

I’ve been trying to create a pause menu for the last couple days. Can some one tell me what I did wrong?

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

public class PauseMenu : MonoBehaviour {

public Canvas pauseMenu;
public Button resumeButton;
public Button optionsButton;
public Button quitToMainMenuButton;
public Button quitGameButton;

void Start()
{
    pauseMenu.enabled = false;
    resumeButton.enabled = false;
    optionsButton.enabled = false;
    quitToMainMenuButton.enabled = false;
    quitGameButton.enabled = false;

    if (Input.GetKeyDown(KeyCode.P))
    {
        pauseMenu.enabled = true;
        resumeButton.enabled = true;
        optionsButton.enabled = true;
        quitToMainMenuButton.enabled = true;
        quitGameButton.enabled = true;
    }
}

public void ResumePress () {
    pauseMenu.enabled = false;
    resumeButton.enabled = false;
    optionsButton.enabled = false;
    quitToMainMenuButton.enabled = false;
    quitGameButton.enabled = false;
}

public void QuitTMM () {
    Application.LoadLevel(0);
}

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

}

I not sure of anything but are you sure you have everything linked though the inspector?
It may not be that you might just have to build it first and test it but that’s all i have now,
I will look into it more