Hi, This is rather weird issue that I am facing with by WCF/Silverlight application. I am using a WCF to get data from a database for my Silverlight application and the completed event is not triggering for method in WCF on some systems. I have checked the called method executes properly has returns the values. I have checked via Fiddler and it clearly shows that response has the returned values as well. However the completed event is not getting triggered. Moreover in few of the systems, everything is fine and I am able to process the returned value in the completed method. Any thoughts or suggestions would be greatly appreciated. I have tried searching around the web but without any luck :( Following is the code.. Calling the method.. void RFCDeploy_Loaded(object sender, RoutedEventArgs e) { btnSelectFile.IsEnabled = true; btnUploadFile.IsEnabled = false; btnSelectFile.Click += new RoutedEventHandler(btnSelectFile_Click); btnUploadFile.Click += new RoutedEventHandler(btnUploadFile_Click); RFCChangeDataGrid.KeyDown += new KeyEventHandler(RFCChangeDataGrid_KeyDown); btnAddRFCManually.Click += new RoutedEventHandler(btnAddRFCManually_Click); ServiceReference1.DataService1Client ws = new BEVDashBoard.ServiceReference1.DataService1Client(); ws.GetRFCChangeCompleted += new EventHandler<BEVDashBoard.ServiceReference1.GetRFCChangeCompletedEventArgs>(ws_GetRFCChangeCompleted); ws.GetRFCChangeAsync(); this.BusyIndicator1.IsBusy = true; } Completed Event.... void ws_GetRFCChangeCompleted(object sender, BEVDashBoard.ServiceReference1.GetRFCChangeCompletedEventArgs e) { PagedCollectionView view = new PagedCollectionView(e.Result); view.GroupDescriptions.Add(new PropertyGroupDescription("RFC")); RFCChangeDataGrid.ItemsSource = view; foreach (CollectionViewGroup group in view.Groups) { RFCChangeDataGrid.CollapseRowGroup(group, true); } this.BusyIndicator1.IsBusy = false; } Please note that this WCF has lots of other method as well and all of them are working fine.... I have problem with only this method... Thanks...