Show Active X page in WPF WebBrowser

I want to display a website (which is Active app) in WPF WebBrowser.

Everything is good when target framework is .NET <= 3.5 but the mandatory is .NET >= 4.0

Then I got exception:

"System.InvalidOperationException: Cannot create more than one System.Windows.Application instance in the same AppDomain.\r\n at System.Windows.Application..ctor()\r\n at WebClientApp.Run_(WebClientApp* , InitializationParams* initParams)\r\n at Eagle.Application.Run(Application* , InitializationParams* )\r\n at WebClientHostControl.AppInitThread_()\r\n at System.Threading.ThreadHelper.ThreadStart_Context(Object state)\r\n at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)\r\n at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)\r\n at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)\r\n at System.Threading.ThreadHelper.ThreadStart()

x:Name="WebBrowser" Source="http://xxxx:38880/webclient/index.html"/>