.DataBindings.Add("SelectedValue", Combo1, "LandID")

Imports System.Data.OleDb
 
Public Class Form1
 
    Private conn As OleDbConnection = Nothing
    Private daLA As OleDbDataAdapter = Nothing
    Private daBL As OleDbDataAdapter = Nothing
    Private daSt As OleDbDataAdapter = Nothing
    Private ds As DataSet = Nothing
    Private WithEvents Combo1 As ComboBox
    Private WithEvents Combo2 As ComboBox
    Private WithEvents Combo3 As ComboBox
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Dim Daten As String
        Daten = Application.StartupPath & "\Daten.mdb"
 
        conn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data" & _
          "Source=I:\Daten.mdb") ' & DatenBank)
        daLA = New OleDbDataAdapter("SELECT ID, Land FROM Laender ORDER BY" & _
        "Land", conn)
        daBL = New OleDbDataAdapter("SELECT ID, LandID, BL FROM Bundeslaender", _
        conn)
        daSt = New OleDbDataAdapter("SELECT ID, Stadt FROM Hauptstadt", conn)
        ds = New DataSet
 
        Combo1 = New ComboBox
 
        With Combo1
            .Font = New Font("Tahoma", 12)
            .SetBounds(10, 10, 150, .Height)
            .DropDownStyle = ComboBoxStyle.DropDownList
        End With
 
        Me.Controls.Add(Combo1)
 
        Combo2 = New ComboBox
        With Combo2
            .Font = Combo1.Font
            .SetBounds(10, 90, 180, .Height)
            .DropDownStyle = ComboBoxStyle.DropDownList
        End With
 
        Me.Controls.Add(Combo2)
 
        Combo3 = New ComboBox
        With Combo3
            .Font = Combo1.Font
            .SetBounds(10, 170, 220, .Height)
            .DropDownStyle = ComboBoxStyle.DropDownList
        End With
 
        Me.Controls.Add(Combo3)
 
        Try
 
            conn.Open()
            daLA.Fill(ds, "Laender")
            daBL.Fill(ds, "Bundeslaender")
            daSt.Fill(ds, "Hauptstadt")
            conn.Close()
 
            With Combo1
                .DataSource = ds.Tables("Laender")
                .DisplayMember = "Land"
                .ValueMember = "ID"
            End With
 
            With Combo2
                .DataSource = ds.Tables("Bundeslaender")
                .DisplayMember = "BL"
                .ValueMember = "LandID"
                ' .DataBindings.Add("SelectedValue", Combo1, "LandID")
            End With
 
            With Combo3
                .DataSource = ds.Tables("Hauptstadt")
                .DisplayMember = "Stadt"
                .ValueMember = "ID"
                '.DataBindings.Add("SelectedValue", Combo2, "ID")
            End With
 
        Catch ex As Exception
 
            MessageBox.Show(ex.Message, "Fehler")
 
        End Try
    End Sub
End Class