I am trying to run this code:

Private Sub Worksheet_Change(ByVal Target As Range)
Charts("Milestone Chart").Activate
With ActiveChart
.HasTitle = True
.ChartTitle.Text = Range("B3") & " " & Range("B4") & " - NLP2"
'"First Quarter Sales"
End With

Application.ScreenUpdating = False
If Target.Address() = "$B$3" Then
Call getMSaddress(Target)
ElseIf Target.Address() = "$B$4" Then
Call getMSaddress(Target)
End If
End Sub

but I am getting the error message on:
Charts("Milestone Chart").Activate

I don't know why this is since I named the chart "Milestone Chart". Any
ideas.
Thanks.