Hello! I have recently started to make a 2D platformer in Unity, and although I have followed several tutorials with different methods, I have came up with the same result continuously - not working. I am using Microsoft's Visual Studio Code. Here is my script - 
using System.Collections;

using System.Collections.Generic;

using UnityEngine;

public class PlayerMovement : MonoBehaviour {

    public float movementSpeed;

    public Rigidbody2D rb;

    float mx;

    private void Update() {

        mx = Input.GetAxisRaw("Horizontal");

    }

    private void FixedUpdate() {

        Vector2 movement = new Vector2(mx * movementSpeed, rb.velocity.y);

        rb.velocity = movement;

 Apparently the code it working for other people, and it should be producing this - 

But I am receiving this - 

I am sure it is something stupid that I am not doing right, but please help. Thanks in advance!

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