Why can't chart component in C# winform display data after data binding?

I'm going to use the dataReader to bind data to C# and chart controls.But currently the table does not display data. There is no display on the Chart control My solution and tried method is as follows: show it on chart control, x axis is time (database variable is Time1), y axis is ranking (database variable is ranking)

private void TmainForm_Load(object sender, EventArgs e) {

    string strconn;
                            //Initializes the connection string
    strconn = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;Connect Timeout=30";
   
    string strSQL;                          //The query command

    DataSet ds1 = new DataSet();            //dataset1：ds1

    //strSQL = "select * from Grade where Sname =N'" + textBox1.Text + "'";

    strSQL = "select ranking,Time1  from Grade ";



    SqlConnection conn = new SqlConnection(strconn);            //Connection object
    conn.Open();
    SqlDataAdapter myDa = new SqlDataAdapter(strSQL, conn);     //DataAdapter
    SqlCommand comm = new SqlCommand();                         //SqlCommand

    comm.Connection = conn;                                     

    comm.CommandText = strSQL;

    comm.CommandType = CommandType.Text;                        

    SqlDataReader dr;
    dr = comm.ExecuteReader();
 


    dataGridView1.DataSource = dr;

    try
    {
        conn.Open();

        myDa.Fill(ds1, "ranking");

        Series dataTable3Series = new Series("dataTable3");          //dataTable3 is the datasource
        dataTable3Series.Points.DataBind(dr, "Time1", "ranking", "");
        dataTable3Series.XValueType = ChartValueType.DateTime;    //Set the Time1  to X-axis
        dataTable3Series.ChartType = SeriesChartType.Line;         //Set the ranking  to Y-axis
        chart1.Series.Add(dataTable3Series);                                //add to chart1                 

** here is the data binding **

        myDa.Dispose();
    }
 

    catch (Exception ex)
    {
        MessageBox.Show(ex.Message, "操作数据库出错！",
            MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
        this.Tag = false;
    }
    finally
    {
        conn.Close();    // close connection
            
    }
    dr.Close();