Problème macro

tablo(i, nMois) = tablo(i, nMois) + (100 - tabloM(i, 1)) / 100 * hrtravjour

Option Explicit

Sub MettreAjour()
Dim wbR As Workbook, f As Worksheet, tablo, tabloM, destination As Range
Dim nomF As String, nMois As Integer, i As Integer, hrtravmois(12) As Integer, hrtravjour As Integer
Dim nmachines As Integer, lettresdest, dest As Worksheet, lettressrc, source As Range, pmachine As Integer
Dim idest As Integer, posmachine As Integer
nomF = "production.xlsm"
On Error Resume Next
Set wbR = Workbooks(nomF)
If Err.Number > 0 Then
    MsgBox "Le classeur ''production'' doit être ouvert;", 16
    Exit Sub
End If
Set dest = ActiveSheet
Set destination = dest.Range("C7:N19")
destination.ClearContents
tablo = destination
nmachines = UBound(tablo, 1)
lettresdest = destination.Offset(0, 1 - destination.Column).Resize(, 1)
For i = 1 To 12
    hrtravmois(i) = 0
Next i
For Each f In wbR.Worksheets
    If IsDate(f.Name) Then
        If Year(CDate(f.Name)) = ActiveSheet.Range("A5") Then
            nMois = Month(CDate(f.Name))
            hrtravjour = f.[R22]
            hrtravmois(nMois) = hrtravmois(nMois) + hrtravjour
            Set source = f.Range("AA9:AA21")
            tabloM = source
            lettressrc = source.Offset(0, 1 - source.Column).Resize(, 1)
            For i = 1 To UBound(tabloM, 1)
                posmachine = 0
                For idest = 1 To nmachines
                    If lettressrc(i, 1) = lettresdest(idest, 1) Then
                        posmachine = idest
                        Exit For
                    End If
                Next idest
                If posmachine > 0 Then
                    tablo(idest, nMois) = tablo(idest, nMois) + (100 - tabloM(i, 1)) / 100 * hrtravjour
                End If
            Next i
        End If
    End If
Next f
For i = 1 To UBound(tablo, 1)
    For nMois = 1 To 12
        If hrtravmois(nMois) <> 0 And tablo(i, nMois) <> 0 Then
            tablo(i, nMois) = tablo(i, nMois) / hrtravmois(nMois)
        Else
            tablo(i, nMois) = ""
        End If
    Next nMois
Next i
destination = tablo
End Sub