Buenas tardes a todos:
Ojala alguien pueda ayudarme con este codigo ya que me esta marcando un error 1004: 
Sub MakeBackup2()
    Dim Archivo$, InvNum$, fn As Variant 
    Workbooks("CALCULO 2010.xlsm").Activate
    ActiveWorkbook.Sheets("Input").Activate 
    InvNum = Range("S3").Value & ".xlsx"
'    Ruta = ActiveSheet.Parent.Path
    Archivo = ActiveSheet.Parent.Path & "\Backup\2010\" & Range("S3").Value & ".xlsx"  
    If Not FileExists(Archivo) Then
        MsgBox "The file doesn't exist!"
        ActiveWorkbook.Sheets("Input").Copy
        ActiveSheet.Shapes("Button 1").Select
        Selection.Delete
        ActiveSheet.Shapes("Button 2").Select
        Selection.Delete
        Cells.Select
        Selection.Copy
        Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
            :=False, Transpose:=False
        Application.CutCopyMode = False
        Range("A8").Select 
    Application.ActivePrinter = "PDFill PDF&Image Writer on Ne01:"
    ExecuteExcel4Macro _
        "PRINT(1,,,1,,,,,,,,2,""PDFill PDF&Image Writer on Ne01:"",,TRUE,,FALSE)"  
        ActiveWorkbook.SaveAs Filename:=Archivo
        ActiveWorkbook.Close (True)
        Workbooks("CALCULO 2010.xlsm").Activate
        Range("S3").Select
    Else
        MsgBox "The file already exists!" & Chr(13) & "Please, enter a new name"
        fn = Application.GetSaveAsFilename(InvNum, "Excel Workbook(*.xlsx),*.xlsx", 1, "Enter the name")
        If TypeName(fn) = "Boolean" Then Exit Sub
        ActiveWorkbook.SaveAs fn
        ActiveWorkbook.Close (True)
        Workbooks("CALCULO 2010.xlsm").Activate
        Range("S3").Select
    End If
End Sub 
Me da error en la linea
        ActiveWorkbook.SaveAs fn 
El error que me da es:  
Código:
 "This extension can not be used with the selected  file type. Change the file extension in the File name text box or select a different file type by changing  the Save as type."
  NOTA: Uso XL 2007. 
Gracias por su ayuda.