Macro insert image on pages defined to print on wdPrinterLowerBin

I need to create a macro in word 2003 that will insert a background image onto all sections of a document where the pages are defined to print on the wdPrinterLowerBin. I am struggling with the code so far I have: -

Sub background()

    Dim x As Integer, background As Shape
   
    x = 1
   
    Do While x <= Selection.Information(wdNumberOfPagesInDocument)
     
    Selection.GoTo What:=wdGoToPage, Which:=wdGoToNext, Name:=x
         
If Selection.PageSetup.FirstPageTray = wdPrinterLowerBin Then
   
    Set background = ActiveDocument.Shapes.AddPicture("\\mbs-server\public\MBS Background\MBSLhead.jpg")
    background.ScaleHeight 1, True
    background.ScaleWidth 1, True
    background.PictureFormat.Brightness = 0.5
    background.PictureFormat.Contrast = 0.5
    background.Height = CentimetersToPoints(29.7)
    background.Width = CentimetersToPoints(21)
    background.LockAspectRatio = True
    background.WrapFormat.AllowOverlap = True
    background.WrapFormat.Side = wdWrapNone
    background.WrapFormat.Type = 2
    background.RelativeHorizontalPosition = _
        wdRelativeVerticalPositionMargin
    background.RelativeVerticalPosition = _
        wdRelativeVerticalPositionMargin
    background.Left = wdShapeCenter
    background.Top = wdShapeCenter
   
End If

x = x + 1

Loop
 
End Sub