Error: datagridviewcomboboxcell value is valid

void FillComboboxCarPlace()
        {
            try
            {
                
                dSet = new DataSet();
                if (con.State == ConnectionState.Closed)
                {
                    con.Open();
                }
                s = "select Move_id , Move_Place from Car_Move_Place";
                sCommand = new SqlCommand(s, con);
                sdAdapter = new SqlDataAdapter();
                sdAdapter.SelectCommand = sCommand;
                sdAdapter.Fill(dSet);
                DataRow dr = dSet.Tables[0].NewRow();
                dr.ItemArray = new object[2] { 0, " ---Select--- " };
                dSet.Tables[0].Rows.InsertAt(dr, 0);
                foreach (DataGridViewRow row in dataGridView1.Rows)
                {
                    int index = 0;
                    var cbxMove = row.Cells[index] as DataGridViewComboBoxCell;
                    //DataGridViewComboBoxCell ContactCombo = (DataGridViewComboBoxCell)(row.Cells["Car_Move_Place"]);
                    ComboMovePlace.ValueMember = "Move_id";
                    ComboMovePlace.DisplayMember = "Move_Place";
                    ComboMovePlace.DataSource = dSet.Tables[0];
                }
                
                if (con.State == ConnectionState.Open)
                {
                    con.Close();
                }
 
            }
            catch
            {
                return;
            }
        }

 private void btn_Search_Click(object sender, EventArgs e)         {             try             {                 dataGridView1.Rows.Clear();                 dataGridView1.Refresh();                                 string s1 = @"SELECT COUNT(*) FROM Move_Transfer WHERE fromDate = @fromDate";                 if (con.State == ConnectionState.Closed)                 {                     con.Open();                 }                                  sCommand = new SqlCommand(s1, con);                 sCommand.Parameters.AddWithValue("@fromDate", dateTimePicker_form.Text);                 int records = (int)sCommand.ExecuteScalar();                 if (records == 0)                 {                     s = " SELECT Place_desc ,Car_id ";                     s = s + " FROM Cars ";                     s = s + "  INNER JOIN  Place ON Cars.Place_id = Place.Place_id ";                     sCommand = new SqlCommand(s, con);                     sdAdapter = new SqlDataAdapter();                     sdAdapter.SelectCommand = sCommand;                     dt = new DataTable();                     sdAdapter.Fill(dt);                                          foreach (DataRow item in dt.Rows)                     {                         int n = dataGridView1.Rows.Add();                         dataGridView1.Rows[n].Cells[0].Value = item["Place_desc"].ToString();                         dataGridView1.Rows[n].Cells[1].Value = item["Car_id"].ToString();                         FillComboboxCarPlace();                     }                                      }                 else                 {                      s = " SELECT Place.Place_desc, Move_Transfer.Car_id, Move_Transfer.busy, Move_Transfer.damage, Move_Transfer.withoutDriver, Car_Move_Place.Move_Place ";                     s = s + " FROM   Move_Transfer ";                     s = s + "  INNER JOIN Cars ";                     s = s + " ON Move_Transfer.Car_id = Cars.Car_id INNER JOIN ";                     s = s + " Place ON Cars.Place_id = Place.Place_id INNER JOIN ";                     s = s + " Car_Move_Place ON Move_Transfer.Move_id = Car_Move_Place.Move_id ";                     s = s + " where fromDate = '" + dateTimePicker_form.Text + "' ";                     sCommand = new SqlCommand(s, con);                     sdAdapter = new SqlDataAdapter();                     sdAdapter.SelectCommand = sCommand;                     dt = new DataTable();                     sdAdapter.Fill(dt);                                          foreach (DataRow item in dt.Rows)                     {                         int n = dataGridView1.Rows.Add();                         dataGridView1.Rows[n].Cells[0].Value = item["Place_desc"].ToString();                         dataGridView1.Rows[n].Cells[1].Value = item["Car_id"].ToString();                         dataGridView1.Rows[n].Cells[2].Value = item["busy"].ToString();                         dataGridView1.Rows[n].Cells[3].Value = item["damage"].ToString();                         dataGridView1.Rows[n].Cells[4].Value = item["withoutDriver"].ToString();                                                dataGridView1.Rows[n].Cells[5].Value = item["Move_Place"].ToString();                     }                     FillComboboxCarPlace();                                       btn_Search.Enabled = false;                 }                                  if (con.State == ConnectionState.Open)                 {                     con.Close();                 }                              }             catch             {                 return;             }         }