Aide sur formule vba

Sub Controler()
Dim DerLigne As Long
Dim Cel As Range, Plage As Range
    Application.ScreenUpdating = False
    With Worksheets("FEV2012")
        Set Plage = .Range("A2:A" & .Range("A" & .Rows.Count).End(xlUp).Row)
    End With
    With Worksheets("GLOBAL")
        DerLigne = .Range("A" & .Rows.Count).End(xlUp).Row
        For Each Cel In .Range("A2:A" & DerLigne)
            If Application.CountIf(Plage, Cel) > 0 Then
                If UCase(Cel.Offset(0, 13)) <> "OK" Then
                    Cel.Offset(0, 13) = "OK"
                Else
                    msg = msg & Chr(10) & "Erreur Ligne " & Cel.Row
                End If
            Else
                Cel.Offset(0, 13) = ""
            End If
        Next Cel
        Set Cel = Nothing
        Set Plage = Nothing
    End With
    Application.ScreenUpdating = True
    If msg <> "" Then MsgBox msg
End Sub