Instantiated Sprite is not rendering.

     // make sure we have ammo and the shoot is not on cooldown
     if(Ammo > 0 && shootTimer <= 0)
     {
         // shoot timer is reset so it's ok to fire.
         if(Input.GetButtonUp("Fire1"))
         {
             Ammo = -1;
             shootTimer = 1.0f;    
             Vector2 direction; // direction the player is facing
             Vector2 gunPos; // position of the Gun on the player
             // which direction is the player travelling / facing?
             if(Input.GetAxis(axisName) < 0)
             {
                 // set the direction the bullet will travel to left
                 direction = -Vector2.right;
                 gunPos = new Vector2 (GameObject.FindGameObjectWithTag("Gun").transform.position.x - 1, // + 1 to stop the bullet from hitting the player
                                       GameObject.FindGameObjectWithTag("Gun").transform.position.y);
             }    
             else
             {    // set the direction the bullet will travel to right
                 direction = Vector2.right;
                 gunPos = new Vector2 (GameObject.FindGameObjectWithTag("Gun").transform.position.x + 1, // + 1 to stop the bullet from hitting the player
                                       GameObject.FindGameObjectWithTag("Gun").transform.position.y);
             }
             // set the bullet to "face" the same direction as the player
             Quaternion quaternionDirection = Quaternion.LookRotation(direction);
             // spawn the bullet
             Instantiate(bullets,gunPos, quaternionDirection);
         }
     }
     else
     {
         // bullet is on Cooldown so let's reflect the passage of time in the timer
         shootTimer -= Time.deltaTime;
     }

 void Update()
 {
     transform.position += transform.forward * speed * Time.deltaTime;
     Destroy (this.gameObject, 20.0f); // destroy after 20 seconds just in case
 }