Rock.Apps.StatementGenerator.SelectAccountsPage.btnNext_Click C# (CSharp) Method

        private void btnNext_Click( object sender, RoutedEventArgs e )
        {
            var accountIds = lstAccounts.Items.OfType<NameIdIsChecked>().Where( a => a.IsChecked == true ).Select( s => s.Id ).ToList();
            if ( accountIds.Count > 0 )
            {
                ReportOptions.Current.AccountIds = accountIds;
                SelectDateRangePage nextPage = new SelectDateRangePage();
                this.NavigationService.Navigate( nextPage );
            }
            else
            {
                lblWarning.Visibility = Visibility.Visible;
            }
        }