/// <summary>
 /// Get invoice by invoice number selected from combo box and fill datagrid
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void InvoiceNumberComBx_SelectionChanged(object sender, EventArgs e)
 {
     try
     {
         if (comboInvoiceNum.SelectedItem != null)
         {
             int iRet = 0;
             ds = db.ExecuteSQLStatement(sql.SelectInvoice((string)comboInvoiceNum.SelectedItem), ref iRet);
             dgInvoices.ItemsSource = new DataView(ds.Tables[0]);
             FillInvoiceComboBox();
         }
     }
     catch (Exception ex)
     {
         HandleError(MethodInfo.GetCurrentMethod().DeclaringType.Name, MethodInfo.GetCurrentMethod().Name, ex.Message);
     }
 }