dropdownlist ไม่เปลี่ยนค่า dropdownlist 1 เลือกค่า แต่พอคลิกเลือก dropdownlist 2 จะเปลี่ยบค่าตาม

Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.OleDb
Partial Class Default8
    Inherits System.Web.UI.Page
    ' Private conStr As String ' = "Provider=Microsoft.Jet.OLEDB.4.0 ;Data Source=" & Server.MapPath("db1.mdb")
    Private conStr As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("db1.mdb") & ";"
    'Private conStr As String = "Server=(local);database=reservation_system;uid=rssadmin;password=PAma22"
    Protected WithEvents droBuild1 As System.Web.UI.WebControls.DropDownList
    Protected WithEvents droFloor1 As System.Web.UI.WebControls.DropDownList
    Private Shared dsChild As New DataSet

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load, Me.Load
        'Put user code to initialize the page here
        If IsPostBack = False Then BindDropDownList()

        Dim objConn As OleDbConnection
        Dim strconnString As String = "Provider=Microsoft.Jet.OLEDB.4.0 ;Data Source=" & Server.MapPath("db1.mdb")
        objConn = New OleDbConnection(strconnString)
        objConn.Open()


        Dim mycommand As New OleDbCommand("Select * From province", objConn)
        GridView1.DataSource = mycommand.ExecuteReader
        GridView1.DataBind()

        objConn.Close()
    End Sub

    Private Sub BindDropDownList()

        Dim conn As New OleDbConnection(conStr)
        conn.Open()
        Dim ds As New DataSet
        Dim da As New OleDbDataAdapter("Select * From province", conn)
        da.Fill(ds, "province")
        DropDownList1.DataSource = ds.Tables("province")
        DropDownList1.DataTextField = ("PROVINCE_NAME")
        DropDownList1.DataValueField = ("PROVINCE_ID") ' binding
        DropDownList1.DataBind()
        da.Dispose()
        conn.Dispose()
        DropDownListChild()
    End Sub

    Private Sub DropDownListChild()

        Dim conn As New OleDbConnection(conStr)
        conn.Open()
        Dim da As New OleDbDataAdapter("SELECT * FROM some1 WHERE PROVINCE_ID ='" & DropDownList1.SelectedItem.Value & "'", conn)
        dsChild = New DataSet
        da.Fill(dsChild, "some1")
        DropDownList2.DataSource = dsChild.Tables("some1")
        DropDownList2.DataTextField = ("Route")
        DropDownList2.DataValueField = ("PROVINCE_ID")
        DropDownList2.DataBind()
        da.Dispose()
        conn.Dispose()
        'DisplayImage()
    End Sub


    'Private Sub DisplayImage()
    ' sSel As String = "FLOOR = " & droFloor.SelectedValue
    '  If dsChild.Tables.Count > 0 Then
    'Dim dr() As DataRow = dsChild.Tables(0).Select(sSel)
    ' Dim Path As String = dr(0)("MAP_PATH")
    '  Response.Write(Path)
    'End If
    ' End Sub

    Private Sub DropDownList_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
        Dim ctrlId As String = CType(sender, DropDownList).ID.ToLower()
        Select Case ctrlId
            Case "Dropdownlist1"
                'DropDownList2.DataBind()
                DropDownListChild()
            Case "Dropdownlist2"

                'DisplayImage()
                ' droFloor.Enabled = True
            Case Else
        End Select
    End Sub
End Class