re, une solution enfin.... en partant de 2 codes glanés sur le site.
Dim x As Integer
x = DatePart("ww", Date, 2, 2)
For i = 2 To Cells(Rows.Count, 6).End(xlUp).Row
T = "SUMIFS(MVTS!$C$3:$C$220,MVTS!$B$3:$B$220," & Range("A" & i).Address & ")"
Cells(i, 6) = Evaluate(T) / x
Next