Private Sub TextBox1_KeyUp(ByVal sender As Object, ByVal e As _
  System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp
        TextBox1.CharacterCasing = CharacterCasing.Upper
        If TextBox1.TextLength = 2 And TextBox1.Text <> "XX" Then TextBox2.Focus()
    End Sub
 
Private Sub TextBox2_KeyUp(ByVal sender As Object, ByVal e As _
  System.Windows.Forms.KeyEventArgs) Handles TextBox2.KeyUp
        TextBox2.CharacterCasing = CharacterCasing.Upper
        If TextBox2.TextLength = 2 And TextBox2.Text <> "XX" Then TextBox3.Focus()
    End Sub