Private Sub Worksheet_Change(ByVal Target As Range)
If (Target.Column = 5 Or Target.Column = 6) And Target.Row > 9 Then
If Cells(Target.Row - 1, "G") < 0 Then
MsgBox "Solde négatif, saisie non autorisée.", vbCritical, "Saisie"
Application.EnableEvents = False: Target = "": Application.EnableEvents = True
End If
End If
End Sub