if (dtbl.Rows.Count > 0)
foreach (DataRow row in dtbl.Rows)
{
DataGridViewComboBoxCell cbCell = (DataGridViewComboBoxCell)dgvLicenseMembers.Rows[0].Cells["dgvCmbNationality"];
cbCell.DataSource = dtbl;
cbCell.DisplayMember = "CountryName";
cbCell.ValueMember = "CountryID";
cbCell.Items.Add(row["CountryName"].ToString()); // ! Getting ERROR -Items collection cannot be modified when the DataSource property is set.
}
sqlCon.Close();