i press space and the player isnot jumping what is wrong? details in description

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class playerController : MonoBehaviour {

public float speed;
public float jumpHeight;
public Rigidbody rigid;

private Vector3 direction;

// Use this for initialization
void Start () {

}

// Update is called once per frame
void Update () {
	direction = new Vector3 (Input.GetAxis ("Horizontal"), 0, Input.GetAxis ("Vertical"));
	if (Input.GetButtonDown ("jump")) {
		rigid.AddForce (Vector3.up * jumpHeight, ForceMode.VelocityChange);
	}
}

private void FixedUpdate ()
{
	rigid.MovePosition(transform.position + direction * speed * Time.fixedDeltaTime);
}

}

try replacing jump with “Space” and make sure t capitalize it.