发生了XamlParseException,该如何解决

发生了XamlParseException
public MainPage()
  {
  InitializeComponent();
  StringBuilder xaml = new StringBuilder();
  xaml.Append("<TextBlock ");
  xaml.Append("xmlns=\"http://schemas.microsoft.com/client/2007\" ");
  xaml.Append("Canvas.Left=\"50\" Canvas.Top=\"30\" FontSize=\"50\" ");
  xaml.Append("FontWeight=\"Bold\" Text=\"动态创建XAML对象\" ");
  //创建TextBlock对象
  TextBlock textblock =(TextBlock)XamlReader.Load(xaml.ToString());
  parentCanvas.Children.Add(textblock);

  xaml = new StringBuilder();
  xaml.Append("<Line Stroke=\"Red\" ");
  xaml.Append("xmlns=\"http://schemas.microsoft.com/client/2007\" ");
  xaml.Append("X1=\"30\" Y1=\"30\" ");
  xaml.Append("X2=\"200\" Y2=\"200\" StrokeThickness=\"3\" ");
  Line line =(Line ) XamlReader.Load(xaml.ToString());
  parentCanvas.Children.Add(line);


  }

  TextBlock textblock =(TextBlock)XamlReader.Load(xaml.ToString());
错误发生在这句

------解决方案--------------------
xaml.Append("<TextBlock ");貌似没有在你的代码中看到结束符吧？还有就是xmlns=\"http://schemas.microsoft.com/....这里面的/会不会发生转义呢。。。。