关于access和mschart数据方面的问题

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load     
      Call accessdelete()
      Dim sConn As String = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=tu.mdb"
      Dim myConnection As New OleDbConnection(sConn)
        Dim myCommand As String = "Select * from tu"
      myConnection.Open()
        Dim custDA As New OleDbDataAdapter(myCommand, myConnection)
        Dim custDS As New DataSet()
        custDA.Fill(custDS, "tu")
        Dim firstView As New DataView
        firstView = custDS.Tables("tu").DefaultView

        Chart1.Series("A班").Points.DataBindXY(firstView, "日期", firstView, "A")
        Chart1.Series("B班").Points.DataBindXY(firstView, "日期", firstView, "B")
        Chart1.Series("C班").Points.DataBindXY(firstView, "日期", firstView, "C")

        custDS.Clear()
        custDS.Dispose()
        custDA.Dispose()

  &nbs