Issue in DatagridView Combobox selecting value - winforms

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 !