protected void showButton_Click(object sender, EventArgs e) { string startDate = FromCalendar.SelectedDate.ToString("d"); string endDate = ToCalendar.SelectedDate.ToString("d"); District newDistrict = new District(); newDistrict.ID = int.Parse(districtDropDownList.SelectedItem.Value); List <Patient> newPatient = aCenterManager.GetPatientList(startDate, endDate, newDistrict); diseaseReportChart.DataSource = newPatient; diseaseReportChart.DataBind(); }