Incompatibilité de type lors de la somme d'objets de type range

Sub sommemoyenne()
Dim somme As Double, plage As Range, ligne As Long
somme = 0
Worksheets(1).[$A$1:$BE$65000].AutoFilter Field:=2, Operator:= _
        xlFilterValues, Criteria1:="=*Saint Jean*"
Set MaPlage = Worksheets(1).UsedRange.SpecialCells(xlCellTypeVisible)
    For ligne = 2 To Range("b" & Rows.Count).End(xlUp).Row
     somme = somme + Worksheets(1).Cells(ligne, 6).Value
    Next
 Worksheets(2).Cells(13, 7).Value = somme / Range("$A$2:$a$27").SpecialCells(xlCellTypeVisible).Count
End Sub

Sub sommemoyenne()
Dim somme As Double
Dim plage As Range
Dim cel As Range

somme = 0
With Worksheets(1)
    .[$A$1:$BE$65000].AutoFilter Field:=2, Criteria1:="Saint Jean*"
    Set MaPlage = .Range("F2:F" & .Cells(Application.Rows.Count, 6).End(xlUp).Row).SpecialCells(xlCellTypeVisible)
End With
For Each cel In MaPlage
    somme = somme + cel.Value
Next
Worksheets(2).Cells(13, 7).Value = somme
End Sub

Sub sommemoyenne()
Dim somme As Double
Dim plage As Range
Dim cel As Range


somme = 0
With Worksheets(1)
    .[$A$1:$BE$65000].AutoFilter Field:=2, Criteria1:="Saint Jean*"
    Set MaPlage = .Range("F2:F" & .Cells(Application.Rows.Count, 6).End(xlUp).Row).SpecialCells(xlCellTypeVisible)
End With
For Each cel In MaPlage
   [COLOR="#FF0000"] If Worksheets(1).Cells(3).Value = "=*08/02/2012*" Then
    somme = somme + cel.Value
    End If[/COLOR]
Next
Worksheets(1).Cells(29, 7).Value = somme
End Sub