C# Word- Dokumenteneigenschaften auslesen

 object Missing = System.Reflection.Missing.Value;
            object BuiltInProps;
            //object CustomProps;
            object n = System.Reflection.Missing.Value;
            object docName = pOrt;
            object onlyread = true;
            object save = false;
            string PropValue = string.Empty;
            
            Word._Document Doc;
            Word.ApplicationClass MyWord = new Word.ApplicationClass();

            //MyWord.Visible = true;
            Doc = MyWord.Documents.Open(ref docName, ref n, ref onlyread, ref n, ref n, ref n,
                                        ref n, ref n, ref n, ref n, ref n, ref n, ref n, ref n, ref n, ref n);
            BuiltInProps = Doc.BuiltInDocumentProperties;

            Type TypeBuiltingProp = BuiltInProps.GetType();

            //Hole den Wert aus dem entsprechendem Feld:
            string Prop = "Keywords"; //"Keywords", "Author", "Title", "Category" sind möglich
            object CatProp = TypeBuiltingProp.InvokeMember("item",
                                                           BindingFlags.Default | BindingFlags.GetProperty, null,
                                                           BuiltInProps, new Object[] {Prop});
            Type TypeAuthorProp = CatProp.GetType();
            PropValue =
                TypeAuthorProp.InvokeMember("Value", BindingFlags.Default | BindingFlags.GetProperty, null,
                                            CatProp, new Object[] {}).ToString();