Extending a Private Sub Worksheet?

Hi Guys,

First I would like to thank you in advance- I know what a help this forum is and it has come to my rescue more times than I have had hot baths.

I am trying to use a macro on my excel sheet. And that lies my problem as I am relatively inexperienced with VBA.

My question- I have used a macro from this site http://excel.tips.net/T003283_Hiding...ell_Value.html) and adapted it for my sheet. See below)

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    If Range("D1").Value = 0 Then
        Columns("H:Q").EntireColumn.Hidden = True
    Else
        Columns("H:Q").EntireColumn.Hidden = False
    End If
End Sub

I would like to add another instance of this (see below)

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    If Range("R1").Value = 0 Then
        Columns("S:V").EntireColumn.Hidden = True
    Else
        Columns("S:V").EntireColumn.Hidden = False
    End If
End Sub

But when I paste it below it - it wont work?

Apologies for being ultra new!

Thanks in advance

Hernan