error when try to use it

[MoAli1Ra23]

this is the waring in output
BINDINGSGENERATOR : warning BG8604: top ancestor CustomEventRewardedVideo not found for nested type MoPub.MobileAds.CustomEventRewardedVideo.ICustomEventRewardedVideoListener.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedAd not found for nested type MoPub.MobileAds.MoPubRewardedAd._1.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._1.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._10.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._11.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._12.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._13.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._14.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._15.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._3.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._5.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._6.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager._9.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager.ForEachMoPubIdRunnable.
1> BINDINGSGENERATOR : warning BG8604: top ancestor MoPubRewardedVideoManager not found for nested type MoPub.MobileAds.MoPubRewardedVideoManager.RequestParameters.
1> BINDINGSGENERATOR : warning BG8604: top ancestor RewardedAdData not found for nested type MoPub.MobileAds.RewardedAdData.TwoPartKey.