Why DataGridView is no-response using backgroundWorker1.RunWorkerAsync()？

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    Int32 TimeFrom, TimeTo;
    ClearGraph();
    /* Clear all list */
    _lstLine.Clear();
    //_lstRestore.Clear();

    _lstRestore._errors.Clear();
    _lstRestore._happentime.Clear();
    _lstRestore._line.Clear();
    _lstRestore._process.Clear();

    lblUpdateTime.Visible = false;

    if (cbTimeFrom.Text == "" || cbTimeTo.Text == "")
    {
        //MessageBox.Show("Nhap thoi gian can tim vao di");
        MessageBox.Show("Select Start and End time");
    }
    else if (cbProcess.Text == "")
        MessageBox.Show("Select Process");//Nhap cong doan can tim kiem vao di
    if (cboMain.Text == "")//cboMain.Text==null
        MessageBox.Show("Select Floor");//Chon Main can tim vao di
    else
    {
        TimeFrom = Convert.ToInt32(cbTimeFrom.Text);
        TimeTo = Convert.ToInt32(cbTimeTo.Text);
        DateTime DateFrom = new DateTime(dtpDateFrom.Value.Year, dtpDateFrom.Value.Month, dtpDateFrom.Value.Day, TimeFrom, 0, 0);
        DateTime DateTo = new DateTime(dtpDateTo.Value.Year, dtpDateTo.Value.Month, dtpDateTo.Value.Day, TimeTo, 59, 59);
        MySqlConnection connection = new MySqlConnection(MyConnectionString);
        try
        {
            connection.Open();
            //db=new DataClassesDataContext(strConnectionString);
        }
        catch (Exception ex)
        {
            MessageBox.Show("Connected to Database errors!: " + ex.Message);
        }

        tblRobotMonitoring temp_lstRestore = new tblRobotMonitoring();
        temp_lstRestore._happentime = new List<DateTime>();
        temp_lstRestore._errors = new List<string>();
        temp_lstRestore._line = new List<string>();
        temp_lstRestore._process = new List<string>();

        MySqlCommand cmd = connection.CreateCommand();
        cmd.CommandText = "set names utf8";
        cmd.ExecuteNonQuery();

        cmd.CommandText = "select HappenTime,Errors,Line,Process from tblRobotMonitoring where HappenTime >= @Time1 and HappenTime<=@Time2";
        cmd.Parameters.Add(new MySqlParameter("@Time1", MySqlDbType.DateTime, 0));
        cmd.Parameters.Add(new MySqlParameter("@Time2", MySqlDbType.DateTime, 0));

        cmd.Parameters["@Time1"].Value = DateFrom;
        cmd.Parameters["@Time2"].Value = DateTo;

        MySqlDataReader rd = cmd.ExecuteReader();
        while (rd.Read())
        {
            DateTime temp_happentime = new DateTime();
            DateTime.TryParse(rd[0].ToString(), out temp_happentime);

            _lstRestore._happentime.Add(temp_happentime);
            _lstRestore._errors.Add(rd[1].ToString());
            _lstRestore._line.Add(rd[2].ToString());
            _lstRestore._process.Add(rd[3].ToString());
        }
        rd.Close();
        cmd.Parameters.Clear();

        connection.Close();

        if (_lstRestore._line.Count() <= 0)
        {

            MessageBox.Show("No Data !");
            lblResult.Text = "Fail SUM : " + _lstRestore._line.Count().ToString();
            lblMainAveResult.Text = "No Data";
            lblResult.Visible = true;

            _lstRestore._errors.Clear();
            _lstRestore._happentime.Clear();
            _lstRestore._line.Clear();
            _lstRestore._process.Clear();

            return;
        }
        else
        {
            lblResult.Visible = true;
            foreach (string va in _lstRestore._line)
            {
                //Add cac line da input du lieu vao he thong
                if (!_lstLine.Contains(va))
                    _lstLine.Add(va);
            }

            var Dictionarys = new Dictionary<string, int>(_lstLine.Count());
            foreach (string line in _lstLine)
            {
                int count = 0;
                foreach (string va in _lstRestore._line)
                {
                    if (va.Equals(line)) ++count;
                }
                //var RecordLine = from tbl in items where (tbl.Line.Equals(line)) select tbl;
                Dictionarys.Add(line, count);
            }
            var take = (from tbl in Dictionarys orderby tbl.Value descending select tbl).Take(100);
            List<string> listLine = new List<string>();
            List<Double> listLineValue = new List<double>();

            foreach (var pair in take)
            {
                listLine.Add(pair.Key);
                listLineValue.Add((double)pair.Value);
            }
            /*  Loc cac loai loi xay ra tren tat ca cac line va hien thi tren data grid view */
            List<string> _lstError = new List<string>();
            List<string> _lstFilteredError = new List<string>();
            /* add cac loi vao list */
            foreach (var va in _lstRestore._errors)
            {
                // if (!_lstError.Contains(va.Errors))
                _lstError.Add(va);
            }
            //hoan thanh 40% cong viec:
            backgroundWorker1.ReportProgress(40);
            /* Clear data grid view */
            dgv1.DataSource = null;
            dgv1.Rows.Clear();
            /* Filter cac loi */
            for (int i = 0; i < _lstError.Count(); i++)
            {
                //them vao progress bar
                int per =40+ 60 *i/ _lstError.Count();
                backgroundWorker1.ReportProgress(per);
                for (int j = 0; j < _lstError.Count(); j++)
                {
                    if (StringCompare(_lstError[i], _lstError[j]))
                    {
                        _lstError[i] = sResult;
                        _lstError[j] = sResult;
                    }

                }
                if (!_lstFilteredError.Contains(sResult))
                    _lstFilteredError.Add(sResult);
            }
            lblResult.Text = "Fail SUM: " + _lstRestore._line.Count().ToString();
            _lstLine = listLine;
            ShowGraph so = new ShowGraph(zg1, "Fail", "Line", "Count", listLine, listLineValue, "Bar");
            foreach (string error in _lstFilteredError)
            {
                var RecordError = from tbl in _lstError where tbl.Equals(error) select tbl;

                dgv1.Rows.Add(error, RecordError.Count());
            }
            dgv1.Refresh();

            lblMainAveResult.Text = (_lstRestore._line.Count() / _lstLine.Count()).ToString();
        }
        /*connection.Close();*/
    }
}