Unity ads initialize error

I can not find this error on internet in ads context so i will show my problem here. i get this error: > MissingMethodException: Method not> found:> 'UnityEngine.Texture2D.LoadImage'.> UnityEngine.Advertisements.Editor.Placeholder.Awake> ()> UnityEngine.Advertisements.Advertisement:Initialize(String,> Boolean) AdManager:Awake() (at> Assets/Scripts/AdManager.cs:12) on this line: Advertisement.Initialize (gameID, true);