Unity - admobs not showing, throwing error

Question

I am trying to show interstitial ads when the player clicks on specific button (hint button), but Unity is giving me this error:

> NullReferenceException: Object reference not set to an instance of an
> object ButtonManager.Hint()...

This is the code for showing the ad:

public class ButtonManager : MonoBehaviour {

    // Use this for initialization
    void Start () {

    }

    // Update is called once per frame
    void Update () {

    }

    public void Reload()
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().name);
    }

    public void Home()
    {
        SceneManager.LoadScene("MainMenu");
    }
    int contc;
    public void Play()
    {
       SceneManager.LoadScene("LevelMenu");
    }
    public void Hint()
    {
        FindObjectOfType<AdMobManager>().Hint = true;
        FindObjectOfType<AdMobManager>().showInterstitial();
    }

Any idea how can I get around this problem?

Answer 1

That is a C# error, you are trying to use a null Object. I think the problem is: FindObjectOfType()

Check if you really get any object with that Find.