function validate(source, arguments) {
  if (document.getElementById('ctl00_Body1_Wizard1_step3OvernightCheckBox')) {
    if (document.getElementById('ctl00_Body1_Wizard1_step3OvernightCheckBox').checked
                                                  && document.getElementById('ctl00_Body1_Wizard1_ddlHotelCategory').value == "Vælg hotelkategori") {
      arguments.IsValid = false;
    }
  }
}