addForce problem please help!

hello , i making a tutorial for fps game , like movement and jumping . im useing addForce to make jump like the tutorial but instead of jumping ith teleporting to the point and falls by gravity. note: im not useing character controller, i create an empty gameobject (like somes tutorials) with camrea as a child. and rigidbody,boxcollider,and my script attach to gameobject. i know this question has asked before ,but i did everything. please see the code ignore the rotation and movment . using UnityEngine; using System.Collections;

public class characterControllerScript : MonoBehaviour {

 public float movmentSpeed = 10f;
 public float mouseSensetivity = 2.5f;
 public float verticalRotationRange = 60f;
 public float jumpForce = 50f;
 private float VerRotation = 0f;
 private double gravity = 0f;
 private float timer = 0f;
 // Use this for initialization
 void Start () {

     Cursor.visible = false;
 }
 
 // Update is called once per frame
 void Update () {
     timer += Time.deltaTime;

     //characterMovment+mouseDirection,depending the mouse facing to so the movment is.
     float horSpeed = Input.GetAxis("Horizontal")*movmentSpeed;
     float verSpeed = Input.GetAxis("Vertical")*movmentSpeed;
     

     float horRotation = Input.GetAxis("Mouse X") * mouseSensetivity;
     transform.Rotate(0, horRotation, 0);

     VerRotation -= Input.GetAxis("Mouse Y") * mouseSensetivity;
     VerRotation = Mathf.Clamp(VerRotation, -verticalRotationRange, verticalRotationRange);
     GetComponentInChildren<Camera>().transform.localRotation=Quaternion.Euler(VerRotation,0,0);
    // Camera.main.transform.localRotation = Quaternion.Euler(VerRotation, 0, 0);
     //  Debug.Log(VerRotation);



     Vector3 speed = new Vector3(horSpeed, 0, verSpeed);
     
     Rigidbody myRG = GetComponent<Rigidbody>();
     speed = transform.rotation * speed;
     myRG.velocity = new Vector3(speed.x,speed.y,speed.z);

     //jumping
     if (Input.GetKeyDown(KeyCode.Space))
     {
      
         GetComponent<Rigidbody>().AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
     }
  

 }

}