Unity C# Object reference not set to an instance of an object

I keep getting the error Object reference not set to an instance of an object on line 64 and I can't figure out what I need to do

Everything is working like the lives are showing up and the timer and the score is but the score isn't increasing if you can tell me what is wrong I would be so thankful

Here's my code:

using UnityEngine;
using System.Collections;

public class Player : MonoBehaviour {

private CountdownTimer myTimer;

private int score = 0;
private int lives = 3;
private int DEATH_Y = -10;

public Texture2D LivesLeft1;
public Texture2D LivesLeft2;
public Texture2D LivesLeft3;

public int GetScore(){
    return score;
}

public int GetLives()
{
    return lives;
}

private void Start()
{
    myTimer = GetComponent<CountdownTimer>();
}

private void Update()
{
    float y = transform.position.y;

    if (y < DEATH_Y) {
        MoveToStartPosition();
        lives--;
    }

    if (score == 10)
    {
        Application.LoadLevel("Level2");
    }

    if (lives == 0)
    {
        Application.LoadLevel("GameOver");
    }

}

private void OnGUI()
{
    GUILayout.BeginHorizontal ();
    DisplayLives();

    int secondsLeft = myTimer.GetSecondsRemaining();//this is line 64
    string timeMessage = "Seconds left = " + secondsLeft;
    GUILayout.Label(timeMessage);

    string scoreMessage = "Score = " + score;
    GUILayout.Label (scoreMessage);
}

private void DisplayLives()
{
    int playerLives = GetLives();

    if (1 == playerLives) {
        GUILayout.Label(LivesLeft1);
    }

    if (2 == playerLives) 
    {
        GUILayout.Label(LivesLeft2);
    }

    if(3 == playerLives){
        GUILayout.Label(LivesLeft3);
    }
}

private void MoveToStartPosition()
{
    Vector3 startPosition = new Vector3(0,5,0);
    transform.position = startPosition;
}

/**
 * what increases the score
 * anything with the tag Hidden
*/
private void OnTriggerEnter(Collider c)
{
    string tag = c.tag;

    if("Hidden" == tag)
    {
        score++;
    }
}
}