Problème Macro PDF

Option Explicit
Dim nomdossier As String
Dim dossier As String
Dim bureau As String
Dim nom As String
Sub Exporter_PDF()
nomdossier = "Tableau_de_bord" 'a adapter nom dossier
cheminbureau
TesteSiDossierExiste
dossier = bureau & "\" & nomdossier & "\"
nom = Sheets("Feuil1").Range("B8") & " " & Range("D4") & ".pdf" ' a adapter nom feuille
Sheets(Array("Feuil1", "Feuil3", "Feuil5", "Feuil7")).Select 'a adapter nom des feuilles
ActiveSheet.ExportAsFixedFormat Type:=xlTypePDF, Filename:= _
        dossier & nom, Quality:=xlQualityStandard, _
        IncludeDocProperties:=True, IgnorePrintAreas:=False, OpenAfterPublish:= _
        True
        MsgBox "Opération réussie", vbInformation, "Enregistrement sur Bureau en pdf"
End Sub
Sub TesteSiDossierExiste()
'https://excel-malin.com/codes-sources-vba/vba-verifier-si-dossier-existe/
Dim MonDossier As String

MonDossier = bureau & "\" & nomdossier

    If DossierExiste(MonDossier) = True Then
       ' MsgBox "Le dossier existe..."
    Else
      MkDir (bureau & "\" & nomdossier)
    End If

End Sub
Public Function DossierExiste(MonDossier As String)
'par Excel-Malin.com ( http://excel-malin.com )

   If Len(Dir(MonDossier, vbDirectory)) > 0 Then
      DossierExiste = True
   Else
      DossierExiste = False
   End If
End Function
Private Sub cheminbureau()
'https://excel-malin.com/codes-sources-vba/trouver-chemin-de-bureau/

    On Error GoTo TestErreur
    Dim cheminbureau As String
    
    cheminbureau = ObtenirCheminBureau()
    
    bureau = cheminbureau 'affiche le chemin vers le dossier Bureau
    Exit Sub
TestErreur:
    MsgBox "Une erreur s'est produite..."
End Sub
Public Function ObtenirCheminBureau() As String
'par: Excel-Malin.com ( https://excel-malin.com )

    On Error GoTo ObtenirCheminBureauError
    Dim cheminbureau As String
    cheminbureau = ""
    Dim oWSHShell As Object
    Set oWSHShell = CreateObject("WScript.Shell")
    
    cheminbureau = oWSHShell.SpecialFolders("Desktop")
    
    If (Not (oWSHShell Is Nothing)) Then Set oWSHShell = Nothing
    ObtenirCheminBureau = cheminbureau

    Exit Function
ObtenirCheminBureauError:
    If (Not (oWSHShell Is Nothing)) Then Set oWSHShell = Nothing
    ObtenirCheminBureau = ""
End Function

dim nomfichier as string
nomfichier= "C:\" & Environ("username") & "\Desktop\Tableau_de_bord\" _
      & Worksheets("8 principaux indicateurs").Range("B8") & " " & Range("D4") & ".pdf"
msgbox nomfichier