Long Dropdownlist values

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim dt As New DataTable
        dt.Columns.Add("Text")
        dt.Columns.Add("Data")
        Dim dr As DataRow = dt.NewRow
        dt.Rows.Add(New Object() {Nothing, Nothing})
        dt.Rows.Add(New Object() {"odd", "Checkbox1~Checkbox3~Checkbox5"})
        dt.Rows.Add(New Object() {"even", "Checkbox2~Checkbox4"})

        DropDownList1.DataValueField = "Data"
        DropDownList1.DataTextField = "Text"
        DropDownList1.DataSource = dt
        DropDownList1.DataBind()
    End If
End Sub

Private Sub DropDownList1_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged
    If DropDownList1.SelectedValue.ToString.Length > 0 Then
        Dim chks() As String = DropDownList1.SelectedValue.ToString.Split("~")
        For i As Integer = 0 To chks.Length - 1
            DirectCast(Me.FindControl(chks(i)), CheckBox).Checked = True
        Next
    Else
        For i As Integer = 1 To 5
            DirectCast(Me.FindControl("Checkbox" & i), CheckBox).Checked = False
        Next
    End If

End Sub