UNITY ADS NOT SHOWING NOT EVEN THE DEMO AD SCREEN

This is my first time with unity ads, I took the code from Unity’s guide. I have changed the project ID. I have followed and done everything they mentioned there. I am using the Advertisement Package from the Package Manager. Ads are also enabled in the Services section. When I click on the The button which plays the Ad it just does nothing. Also Test mode is enabled since I am in Unity only.

My code:
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Advertisements;

[RequireComponent (typeof (Button))]
public class RewardedAdsButton : MonoBehaviour, IUnityAdsListener {

#if UNITY_IOS
private string gameId = "";
#elif UNITY_ANDROID
private string gameId = "";
#endif

Button myButton;
public string mySurfacingId = "rewardedVideo";

void Start () {   
    myButton = GetComponent <Button> ();

    // Set interactivity to be dependent on the Ad Unit or legacy Placement’s status:
    myButton.interactable = Advertisement.IsReady (mySurfacingId); 

    // Map the ShowRewardedVideo function to the button’s click listener:
    if (myButton) myButton.onClick.AddListener (ShowRewardedVideo);

    // Initialize the Ads listener and service:
    Advertisement.AddListener (this);
    Advertisement.Initialize (gameId, false);
}

// Implement a function for showing a rewarded video ad:
public void ShowRewardedVideo () {
    Advertisement.Show (mySurfacingId);
}

// Implement IUnityAdsListener interface methods:
public void OnUnityAdsReady (string surfacingId) {
    // If the ready Ad Unit or legacy Placement is rewarded, activate the button: 
    if (surfacingId == mySurfacingId) {        
        myButton.interactable = true;
    }
}

public void OnUnityAdsDidFinish (string surfacingId, ShowResult showResult) {
    // Define conditional logic for each ad completion status:
    if (showResult == ShowResult.Finished) {
        // Reward the user for watching the ad to completion.
    } else if (showResult == ShowResult.Skipped) {
        // Do not reward the user for skipping the ad.
    } else if (showResult == ShowResult.Failed) {
        Debug.LogWarning ("The ad did not finish due to an error.");
    }
}

public void OnUnityAdsDidError (string message) {
    // Log the error.
}

public void OnUnityAdsDidStart (string surfacingId) {
    // Optional actions to take when the end-users triggers an ad.
} 

}

try to disable test mode