protected void ddlTotalInstallments_SelectedIndexChanged(object sender, EventArgs e) { if (ddlTotalInstallments.SelectedIndex == 0 || ddlStartDate.SelectedIndex == 0 || ddlFrequency.SelectedIndex == 0) { return; } DateTime dtEndDate = boOnlineOrder.GetSipEndDate(Convert.ToDateTime(ddlStartDate.SelectedValue), ddlFrequency.SelectedValue, Convert.ToInt32(ddlTotalInstallments.SelectedValue) - 1); lblEndDateDisplay.Text = dtEndDate.ToString("dd-MMM-yyyy"); }