C# combobox set custom DiplayMember

I'm binding combobox to a DataTable (table columns are "NAME", "SURNAME" and "ID"). Currently I have set ValueMember to "ID", and DisplayMember to "SURNAME". I wish to change DisplayMember - and DisplayMember only. By reading all sorts of documentation (including this forum) It can be achieved by exposing a custom property and bind combobox to that, however I'm having difficulties with It.

Closest solution was found here where you can format combobox, but that changes ValueMember too. Though under accepted answer is mentioned that you can do same with only DisplayMember by exposing a property...

So I tried with this:

  private string _employee;  public string MyDisplay        {            get            {                DataRowView r = (DataRowView)this.SelectedItem;                DataRow s = r.Row;                return _employee= s["SURNAME"].ToString() +""+ s["NAME"].ToString();            }            set            {                this._employee = value;            }        }

But that doesn't display my custom DisplayMember when I bind It to MyDisplay, when I scroll combobox Items It's Text is only System.Data.DataRowView.

What is the correct way to accomplish this ?

EDIT:

My full code for binding comboboxes:

 private void FillCombobox()        {            var dt = new DataTable();            try            {                using (var conn = new OracleConnection(conn_string))                {                       using (OracleCommand cmd = new OracleCommand("MYSCHEMA.EMPLOYEES"))                    {                        cmd.Connection = conn;                        cmd.CommandType = CommandType.StoredProcedure;                        cmd.Parameters.Add(new OracleParameter("CHOOSE_SELECT_IN", OracleDbType.Decimal, 6, ParameterDirection.Input));                        cmd.Parameters.Add(new OracleParameter("RESULT_OUT", OracleDbType.RefCursor)).Direction = ParameterDirection.Output;                        using (OracleDataAdapter da = new OracleDataAdapter())                        {                            da.SelectCommand = cmd;                            da.Fill(dt);                        }                    //bind combobox                    BindData(dt, Combobox1, "MyDisplay", "ID");              }            }            catch (Exception ex)            {                MessageBox.Show(ex.Message);                return;            }        }        private void BindData(DataTable dt, ComboBox ctl, string displayMember, string valueMember)        {            if (ctl.InvokeRequired)            {                ctl.Invoke(new Action<DataTable, ComboBox, string, string>(BindData),                               dt,                               ctl,                               displayMember,                               valueMember);            }            else            {                ctl.DisplayMember = displayMember;                ctl.ValueMember = valueMember;                ctl.DataSource = dt;                ctl.Text = "";                ctl.SelectedIndex = -1;            }        }