public void Execute(object parameter) { _canExecute = false; var flvm = (FolderListVM) parameter; var fs = new FileServiceClient(); var p = flvm.Parent; flvm.Filelist.Clear(); fs.ListFilesCompleted += (sender, args) => { var lst = args.Result; foreach (var l in lst) { flvm.Filelist.Add(l); flvm.FilelistStr.Add(l.FileName); } }; fs.ListFilesAsync(Path.Combine(flvm.ClientRepository,flvm.SelectedFolder),flvm.FileExtension); _canExecute = true; }