สอบถามเรื่องการ binding ข้อมูลของ combobox แล้วerrorค่ะ

   Private Sub cboDep1_SelectedValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboDep1.SelectedValueChanged
        Dim strConn As String
        strConn = DBConnString.strConn
        Conn = New SqlConnection()

        With Conn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = strConn
            .Open()
        End With

        sb = New StringBuilder()
        sb.Append("SELECT * FROM tbl_dep2")
        sb.Append(" WHERE dep1ID ='" & cboDep1.SelectedValue.ToString & "'")

        Dim sqlIni As String
        sqlIni = sb.ToString()

        If isFind2 = True Then
            ds.Tables("tbl_dep2").Clear()
        End If

        da = New SqlDataAdapter(sqlIni, Conn)
        da.Fill(ds, "tbl_dep2")
        With cboDep2
            .DataSource = ds.Tables("tbl_dep2")
            .DisplayMember = "dep2Name"
            .ValueMember = "dep2ID"
        End With
        isFind2 = True

        iDep1.SelectedValue = cboDep1.SelectedValue
    End Sub


    Private Sub frmPeople_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        lblPeopleID.BackColor = Color.FromArgb(0, 0, 0, 0)

        Dim FD As New FormFader
        FD.FadeIn(Me, 0.25)

        sw.Reset()
        sw.Start()
        Dim strConn As String
        strConn = DBConnString.strConn

        Conn = New SqlConnection()
        With Conn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = strConn
            .Open()
        End With

        sb = New StringBuilder()
        sb.Append("SELECT * FROM tbl_preT;")
        sb.Append("SELECT * FROM tbl_preE;")
        sb.Append("SELECT * FROM tbl_type;")
        sb.Append("SELECT * FROM tbl_campus;")
        sb.Append("SELECT * FROM tbl_dep1 ORDER BY dep1Name;")
        sb.Append("SELECT * FROM tbl_dep2 ORDER BY dep2Name;")

        Dim sqlIni As String
        sqlIni = sb.ToString()

        RemoveHandler cboPreT.SelectedValueChanged, AddressOf cboPreT_SelectedValueChanged
        RemoveHandler cboPreE.SelectedValueChanged, AddressOf cboPreE_SelectedValueChanged
        RemoveHandler cboCampus.SelectedValueChanged, AddressOf cboCampus_SelectedValueChanged
        RemoveHandler cboDep1.SelectedValueChanged, AddressOf cboDep1_SelectedValueChanged
        RemoveHandler cboDep2.SelectedValueChanged, AddressOf cboDep2_SelectedValueChanged
        RemoveHandler cboType.SelectedValueChanged, AddressOf cboType_SelectedValueChanged

        com = New SqlCommand()
        With com
            .CommandText = sqlIni
            .CommandType = CommandType.Text
            .Connection = Conn

            dr = .ExecuteReader()
            If dr.HasRows Then

                dtPreT = New DataTable
                dtPreT.Load(dr)
                With cboPreT
                    .BeginUpdate()
                    .DisplayMember = "preTNameS"
                    .ValueMember = "preTID"
                    .DataSource = dtPreT
                    .EndUpdate()
                End With

                dtPreE = New DataTable
                dtPreE.Load(dr)
                With cboPreE
                    .BeginUpdate()
                    .DisplayMember = "preENameS"
                    .ValueMember = "preEID"
                    .DataSource = dtPreE
                    .EndUpdate()
                End With

                dtType = New DataTable
                dtType.Load(dr)
                With cboType
                    .BeginUpdate()
                    .DisplayMember = "typeName"
                    .ValueMember = "typeID"
                    .DataSource = dtType
                    .EndUpdate()
                End With

                dtCampus = New DataTable
                dtCampus.Load(dr)
                With cboCampus
                    .BeginUpdate()
                    .DisplayMember = "CampusNameS"
                    .ValueMember = "campusID"
                    .DataSource = dtCampus
                    .EndUpdate()
                End With

                dtDep1 = New DataTable
                dtDep1.Load(dr)
                da = New SqlDataAdapter(sqlIni, Conn)
                ' da.Fill(ds, "tbl_dep1")
                With cboDep1
                    .BeginUpdate()
                    .DisplayMember = "dep1Name"
                    .ValueMember = "dep1ID"
                    .DataSource = dtDep1
                    .EndUpdate()
                End With

                

                dtDep2 = New DataTable
                dtDep2.Load(dr)
                With cboDep2
                    .BeginUpdate()
                    .DisplayMember = "dep2Name"
                    .ValueMember = "dep2ID"
                    .DataSource = dtDep2
                    '.DataSource = ds.Tables("tbl_dep1")
                    .EndUpdate()
                End With

            End If

        End With
        dr.Close()