在WindowsFormsHost中插入窗体时出现ArgumentException

在WPF应用程序中,我创建WindowsFormsHost并希望在其中插入Form包含COM/ Activex控件.但后来我得到:

A first chance exception of type 'System.ArgumentException' occurred in WindowsFormsIntegration.dll
   at System.Windows.Forms.Integration.WindowsFormsHost.set_Child(Control value)
   at HomeSecurity.MainWindow..ctor() w c:\Users\R\Documents\Visual Studio 2013\Projects\HomeSecurity\HomeSecurity\MainWindow.xaml.cs:row 26
'HomeSecurity.vshost.exe' (CLR v4.0.30319: HomeSecurity.vshost.exe): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\UIAutomationTypes\v4.0_4.0.0.0__31bf3856ad364e35\UIAutomationTypes.dll'. Symbols loaded.

这是MainWindow.的结构.类VideoStream扩展了类Form

      public MainWindow() {
           InitializeComponent();
           VideoStream VideoStream = new VideoStream();//creating a Form containing Activex control
           WindowsFormsHost Host = new WindowsFormsHost();//creating a host
           try {
               Host.Child = VideoStream;//setting content of Host, CAUSES THE EXCEPTION PRINTED ABOVE
           }catch(Exception e){
               Console.WriteLine(e.StackTrace);//output above
           }
        }

我不能长时间处理它,我没有时间了.如何解决这个问题？