Unity ads not showing rewarded video ad.

Hi, I am using unity ads from service window, normal add ir working fine but when it comes to rewarded ad it is not popping up.

 Debug.Log(Advertisement.IsReady("rewardedVideoZone"));

this line always return a false value.

This is my configuration in service window.

And this is the code for showing rewarded ad.

  public void ShowRewardedAd()
       {
           Debug.Log(Advertisement.IsReady("rewardedVideoZone"));
         if (Advertisement.IsReady("rewardedVideoZone"))
         {
           var options = new ShowOptions { resultCallback = HandleShowResult };
           Advertisement.Show("rewardedVideoZone", options);
         }
       }
     
       private void HandleShowResult(ShowResult result)
       {
         switch (result)
         {
           case ShowResult.Finished:
             Debug.Log("The ad was successfully shown.");
             //
             // YOUR CODE TO REWARD THE GAMER
             // Give coins etc.
             break;
           case ShowResult.Skipped:
             Debug.Log("The ad was skipped before reaching the end.");
             break;
           case ShowResult.Failed:
             Debug.LogError("The ad failed to be shown.");
             break;
         }
       }

Any help will be highly appreciated.