Script interaction with other objects in unity?

Question

C++ / C#

GameObject respawn;
    ParticleSystem ps;
 void Start() {
        gb = GetComponent<Transform>();
        camera1 = Camera.main;
        camera2 = GetComponent<Camera>();
        camera2.enabled = false;
        camera1.enabled = true;
        respawn = GameObject.FindGameObjectWithTag("Respawn");
        ParticleSystem ps = (ParticleSystem)respawn.GetComponent(typeof(ParticleSystem));
    }
 void Update() {
if (Input.GetMouseButton(0) && gb.transform.rotation.x != 180 && gb.transform.rotation.y != 90)
        {
           
        
            gb.LookAt(Input.mousePosition);
            gb.Rotate(new Vector3(Input.mousePosition.x, Input.mousePosition.y, 0f),0f,Space.World);
            ps.transform.position = Input.mouseScrollDelta;
            ps.Play();

        }

ParticleSystem ps = (ParticleSystem)respawn.GetComponent(typeof(ParticleSystem))‌​;

do not tell me why I have a NullReferenceException here?
This is despite the fact that in

GameObject respawn = GameObject.FindGameObjectWithTag("Respawn");

- the tag on the object is assigned to me;
well, more precisely, it swears at ps.transform.position = Input.mouseScrollDelta;
but gives exactly NullReferenceException - therefore it swears at the line

ParticleSystem ps = (ParticleSystem)respawn.GetComponent(typeof(ParticleSystem))‌​;

Answer 1

So there is no ParticleSystem component on the respawn object. Use a debugger to find exactly what is missing. When you understand that when the function is called null, then the further algorithm for solving the problem will be clear.