Problème avec INDIRECT.EXT

Function Pull(xref As String) As Variant
  'inspired by Bob Phillips and Laurent Longre
  'but written by Harlan Grove
  '-----------------------------------------------------------------
  'Copyright (c) 2003 Harlan Grove.
  '
  'This code is free software; you can redistribute it and/or modify
  'it under the terms of the GNU General Public License as published
  'by the Free Software Foundation; either version 2 of the License,
  'or (at your option) any later version.
  '-----------------------------------------------------------------

  Dim xlapp As Object, xlwb As Workbook
  Dim b As String, r As Range, C As Range, n As Long

  n = InStrRev(xref, "\")

  If n > 0 Then
    If Mid(xref, n, 2) = "\[" Then
      b = Left(xref, n)
      n = InStr(n + 2, xref, "]") - n - 2
      If n > 0 Then b = b & Mid(xref, Len(b) + 2, n)

    Else
      n = InStrRev(Len(xref), xref, "!")
      If n > 0 Then b = Left(xref, n - 1)

    End If

    If Left(b, 1) = "'" Then b = Mid(b, 2)

    On Error Resume Next
    If n > 0 Then If Dir(b) = "" Then n = 0
    Err.Clear
    On Error GoTo 0

  End If

  If n <= 0 Then
    Pull = CVErr(xlErrRef)
    Exit Function
  End If

  Pull = Evaluate(xref)

  If IsArray(Pull) Then Exit Function

  If CStr(Pull) = CStr(CVErr(xlErrRef)) Then
    On Error GoTo CleanUp

    Set xlapp = CreateObject("Excel.Application")
    Set xlwb = xlapp.Workbooks.Add      'needed by .ExecuteExcel4Macro

    On Error Resume Next

    n = InStr(InStr(1, xref, "]") + 1, xref, "!")
    b = Mid(xref, 1, n)

    Set r = xlwb.Sheets(1).Range(Mid(xref, n + 1))

    If r Is Nothing Then
      Pull = xlapp.ExecuteExcel4Macro(xref)
    Else
      For Each C In r
        C.Value = xlapp.ExecuteExcel4Macro(b & C.Address(1, 1, xlR1C1))
      Next C
      Pull = r.Value
    End If

CleanUp:
    If Not xlwb Is Nothing Then xlwb.Close 0
    If Not xlapp Is Nothing Then xlapp.Quit
    Set xlapp = Nothing

  End If

End Function