Issue in DatagridView Combobox selecting value

Question

i have the XML which i am assigning to the datagridview combobox, in which 5 values are there, all values are having same CountyName but different CountyID.

  <CityCounty>
    <CountyID xmlns="http:// ">25</CountyID>
    <CountyName xmlns="http">Washington Township</CountyName>
    <StateID xmlns="http:">NJ</StateID>
    <TaxDistrictCode xmlns="http:// ">552</TaxDistrictCode>
  </CityCounty>

  <CityCounty>
    <CountyID xmlns="http: ">26</CountyID>
    <CountyName xmlns="http">Washington Township</CountyName>
   <StateID xmlns="http: ">NJ</StateID>
    <TaxDistrictCode xmlns="http">553</TaxDistrictCode>
  </CityCounty>

  <CityCounty>
    <CountyID xmlns="http: ">27</CountyID>
    <CountyName xmlns="http">Washington Township</CountyName>
   <StateID xmlns="http: ">NJ</StateID>
    <TaxDistrictCode xmlns="http">553</TaxDistrictCode>
  </CityCounty>

  <CityCounty>
    <CountyID xmlns="http: ">28</CountyID>
    <CountyName xmlns="http">Washington Township</CountyName>
   <StateID xmlns="http: ">NJ</StateID>
    <TaxDistrictCode xmlns="http">554</TaxDistrictCode>
  </CityCounty>

  <CityCounty>
    <CountyID xmlns="http: ">29</CountyID>
    <CountyName xmlns="http">Washington Township</CountyName>
   <StateID xmlns="http: ">NJ</StateID>
    <TaxDistrictCode xmlns="http">555</TaxDistrictCode>
  </CityCounty>

i am assigning the display member of the datagridview combobox as CountyName and value member as CountyID

List<ClassCityCounty> cityCountyList1;
var s = new XmlSerializer(typeof(List<CityCounty>));
var path = EnvironmentPath.GetEnvironmentPath() + @"\XML\CityCounty.xml";
    var r = new StreamReader(@path);
    cityCountyList1 = (List<CityCounty>)s.Deserialize(r);
    r.Close();

DataGridViewComboBoxCell dgvCbo = dgvGridName[colindex, rowindex] as DataGridViewComboBoxCell;
dgvCbo.DataSource = cityCountyList1; //list value - parsed from XML
dgvCbo.DisplayMember = Constants.CITYCOUNTYNAME;
dgvCbo.ValueMember = Constants.COUNTYID;

once i user select the any of the values i need to fetch the selected CountyID from the droupdown and need to pass for the further operation.

string testid = dgvGridName.CurrentRow.Cells[colindex].Value.ToString()

but whatever the value i am selecting from the dropdown, i am getting the same CountyID 28 for the above string testid. i should get different CountyID for the each value, but i am getting same CountyID So any can please suggest me what i am doing wrong and suggest some solution. thanks in Advance !