recherche dans deux fichiers différents

 If Not IsDate(cDest) Then
            Set cSource = PlageSource.Columns(1).Find(what:=cDest(1, -5), _
                                After:=PlageSource(1, 1), _
                                LookIn:=xlValues, _
                                lookAt:=xlWhole, _
                                searchorder:=xlByRows)
            If Not cSource Is Nothing Then
                If IsDate(cSource(1, 5)) Then
                    cDest = cSource(1, 5)
                    cDest.Interior.ColorIndex = 4
            End If
        End If

Private Sub cmdRechercher_Click()
    Dim wk As Workbook, PlageSource As Range, cSource As Range, cDest As Range
    Dim ModeCalcul As XlCalculation
    ModeCalcul = Application.Calculation
 
    On Error Resume Next
    Set wk = Workbooks("Suivi Intervention.xls")
    On Error GoTo 0
    If wk Is Nothing Then
        MsgBox "Vérifiez que le classeur 'Suivi Intervention.xls' soit ouvert et recommencez", vbExclamation, "Recherche dates paiement"
        Exit Sub
    End If
 
 
    ModeCalcul = Application.Calculation
    Set PlageSource = wk.Sheets("Feuil1").Range("A1").CurrentRegion
 
    On Error GoTo FIN
    With Application
        .Calculation = xlCalculationManual
        .EnableEvents = False
        .ScreenUpdating = False
    End With
    For Each cDest In Me.Range("A1").CurrentRegion.Columns(7).Cells
        If Not IsDate(cDest) Then
            Set cSource = PlageSource.Columns(1).Find(what:=cDest(1, -5), _
                                After:=PlageSource(1, 1), _
                                LookIn:=xlValues, _
                                lookAt:=xlWhole, _
                                searchorder:=xlByRows)
            If Not cSource Is Nothing Then
                If IsDate(cSource(1, 5)) Then
                    cDest = cSource(1, 5)
                    cDest.Interior.ColorIndex = 4
            End If
        End If
    Next
 
FIN:
    With Application
        .Calculation = ModeCalcul
        .EnableEvents = True
        .ScreenUpdating = True
    End With
End Sub