Private Sub TextBox_KeyUp(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp, _
      TextBox2.KeyUp, TextBox3.KeyUp
        Dim tb As TextBox = CType(sender, TextBox)
        Dim index As Integer
 
        If Integer.TryParse(tb.Name.Substring(7), index) Then
            If tb.TextLength = 2 And tb.Text.ToUpper <> "XX" Then
                Me.Controls("Textbox" & index + 1).Focus()
            End If
        End If
    End Sub