Getting Error At Designing Time and Run Time

[Jack]

Hello To All

I m getting error in silverlight application actully i m using wcf (With linq) to bind treeview.

All things are going fine it build succeeded but when i debug it showing error like

An exception occurred during the operation, making the result invalid.  Check InnerException for exception details.

   at System.ComponentModel.AsyncCompletedEventArgs.RaiseExceptionIfNecessary()
   at NewTreeviewApp.ServiceReference1.GetTreeviewCompletedEventArgs.get_Result()
   at NewTreeviewApp.HierarchicalDataSource.webService_GetTreeviewCompleted(Object sender, GetTreeviewCompletedEventArgs e)
   at NewTreeviewApp.ServiceReference1.Service1Client.OnGetTreeviewCompleted(Object state)


and designing time error is like

in attach file