[Private Sub btnPrüfer_Click()
    If txtBenutzername.Text = "testname" And txtPasswort.Text = "testpw" Then
    this.Hide
    Lader.Show
  End If
End Sub

Private Sub Form_Load()
   ' Datenbank öffnen
   Dim Db As Database
   Dim Tabelle As Recordset
   Dim dbFile As String
   dbFile = App.Path + "\KARTEI.MDB"
   Set Db = Workspaces(0).OpenDatabase(dbFile, False, False)
   Set Tabelle = Db.OpenRecordset("Karteien")
End Sub