Character not double Jump

Live Training 20 Jan 2014 - LMG: 2D Infinite Runner - https://www.youtube.com/watch?v=7dP7R-GbFkM (20:20)

My character not jump. I'm using Unity 5.4

using UnityEngine;

namespace UnitySampleAssets._2D {

 public class PlatformerCharacter2D : MonoBehaviour
 {
     private bool facingRight = true; // For determining which way the player is currently facing.

     [SerializeField] private float maxSpeed = 10f; // The fastest the player can travel in the x axis.
     [SerializeField] private float jumpForce = 400f; // Amount of force added when the player jumps.    

     [Range(0, 1)] [SerializeField] private float crouchSpeed = .36f;
     // Amount of maxSpeed applied to crouching movement. 1 = 100%

     [SerializeField] private bool airControl = false; // Whether or not a player can steer while jumping;
     [SerializeField] private LayerMask whatIsGround; // A mask determining what is ground to the character

     private Transform groundCheck; // A position marking where to check if the player is grounded.
     private float groundedRadius = .2f; // Radius of the overlap circle to determine if grounded
     private bool grounded = false; // Whether or not the player is grounded.
     private Transform ceilingCheck; // A position marking where to check for ceilings
     private float ceilingRadius = .01f; // Radius of the overlap circle to determine if the player can stand up
     private Animator anim; // Reference to the player's animator component.

     bool doubleJump = false;

     private void Awake()
     {
         // Setting up references.
         groundCheck = transform.Find("GroundCheck");
         ceilingCheck = transform.Find("CeilingCheck");
         anim = GetComponent<Animator>();
     }


     private void FixedUpdate()
     {
         // The player is grounded if a circlecast to the groundcheck position hits anything designated as ground
         grounded = Physics2D.OverlapCircle(groundCheck.position, groundedRadius, whatIsGround);
         anim.SetBool("Ground", grounded);

         // Set the vertical animation
         anim.SetFloat("vSpeed", GetComponent<Rigidbody2D>().velocity.y);

         if (grounded)
         {
             doubleJump = false;
         }
     }


     public void Move(float move, bool crouch, bool jump)
     {


         // If crouching, check to see if the character can stand up
         if (!crouch && anim.GetBool("Crouch"))
         {
             // If the character has a ceiling preventing them from standing up, keep them crouching
             if (Physics2D.OverlapCircle(ceilingCheck.position, ceilingRadius, whatIsGround))
                 crouch = true;
         }

         // Set whether or not the character is crouching in the animator
         anim.SetBool("Crouch", crouch);

         //only control the player if grounded or airControl is turned on
         if (grounded || airControl)
         {
             // Reduce the speed if crouching by the crouchSpeed multiplier
             move = (crouch ? move*crouchSpeed : move);

             // The Speed animator parameter is set to the absolute value of the horizontal input.
             anim.SetFloat("Speed", Mathf.Abs(move));

             // Move the character
             GetComponent<Rigidbody2D>().velocity = new Vector2(move*maxSpeed, GetComponent<Rigidbody2D>().velocity.y);

             // If the input is moving the player right and the player is facing left...
             if (move > 0 && !facingRight)
                 // ... flip the player.
                 Flip();
             // Otherwise if the input is moving the player left and the player is facing right...
             else if (move < 0 && facingRight)
                 // ... flip the player.
                 Flip();
         }
         // If the player should jump...
         if ((grounded || !doubleJump) && jump && anim.GetBool("Ground"))
         {
             // Add a vertical force to the player.
             grounded = false;
             anim.SetBool("Ground", false);

             GetComponent<Rigidbody2D>().velocity = new Vector2 (GetComponent<Rigidbody2D>().velocity.x, 0);

             GetComponent<Rigidbody2D>().AddForce(new Vector2(0f, jumpForce));

             if (!grounded) 
             {
                 doubleJump = true;
             }
         }
     }


     private void Flip()
     {
         // Switch the way the player is labelled as facing.
         facingRight = !facingRight;

         // Multiply the player's x local scale by -1.
         Vector3 theScale = transform.localScale;
         theScale.x *= -1;
         transform.localScale = theScale;
     }
 }

}