Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Dim cel As Range, réf$, qté%
With Target.Cells(1)
If .Address <> "$J$2" Then Exit Sub
réf = [E2]: If réf = "" Then Exit Sub
Set cel = Columns(12).Find(réf, , -4163, 1, 1)
If cel Is Nothing Then Exit Sub
qté = Val(.Value)
Cells(cel.Row, 13) = IIf(qté = 0, "", qté)
End With
End Sub