CustomControlLibrary的Generic.xaml中的ResourceDictionary会产生错误

I'm making a WPF-CustomControlLibrary-Project with some customcontrols. One of these is a Label with a nested TextBlock for TextWrapping. When i set the DependencyProperty HorizontalContentAlignement p.e. to Left, i want the TextAlignment of the Textblock set to Left too. So i implememented a converter class like in the article here:I'm making a WPF-CustomControlLibrary-Project w