protected void ProcessButton_Click(object sender, EventArgs e) { // build data int maxItems = AlwaysConvert.ToInt(list_TopCount.SelectedValue, 10); IList <SalesByProvinceSummary> rptData = ReportDataSource.GetSalesByState(list_Country.SelectedValue, StartDate.SelectedDate, EndDate.SelectedDate, maxItems, 0, "TotalSales DESC"); Chart1.Visible = rptData.Count > 0; BuildCharts(rptData); }