Private Sub ComboBox1_Change()
Dim DR As Integer
If Me.ComboBox1.ListIndex = -1 Then Me.TextBox1.Value = "": Exit Sub
With Sheets("DONNEES")
DR = .Range("A" & .Rows.Count).End(xlUp).Row
Me.TextBox1.Value = Application.SumIf(.Range("A3:A" & DR), Me.ComboBox1, .Range("b3:b" & DR))
End With
End Sub