I am trying Roll a Ball unity tutorial.Everything is fine,but when I roll the ball it is moving through the cube instead of picking it. my player class is

using UnityEngine;

using System.Collections;

public class player : MonoBehaviour { public float speed; // Use this for initialization

// Update is called once per frame
void Update () {
    float h = Input.GetAxis("Horizontal");

float v = Input.GetAxis("Vertical");
    Vector3 move = new Vector3(h,0,v);
    rigidbody.AddForce(move * speed * Time.deltaTime);


}
void OnTriggerEnter(Collider other)
{
    if(other.gameObject.tag == "Pick up")
    {
    other.gameObject.SetActive(false);
    }
}

}