I'm resolved
in my AppBootstrapper.cs i'm insert
private void LoadDictionary()
{
var dictionaries = App.Current.Resources.MergedDictionaries;
dictionaries.Clear();
var themeStyles = new ResourceDictionary { Source = new Uri("/MyAssemblyName;component/Styles/Styles.xaml", UriKind.RelativeOrAbsolute) };
dictionaries.Add(themeStyles);
}
And it works!