public SearchControl(CARSPage page, User rootManager) { InitializeComponent(); SetPageAndUser(page, rootManager); chkShowAll.IsChecked = CarsConfig.Instance().ShowAllRecords; CARSServiceClient client = CARSServiceClientFactory.CreateCARSServiceClient();// leave this line, we cannot use a public static object here. Because it may already has handler of GetLeaveTypesCompleted client.GetLeaveTypesCompleted += new EventHandler <GetLeaveTypesCompletedEventArgs>(client_GetLeaveTypesCompleted); client.GetLeaveTypesAsync(); }