Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("b2")) Is Nothing Then
With Sheets(Replace((Sheets("graph").Range("B2").Value), " ", ""))
Set chrtdata = .Range(.Range("B1"), .Range("E" & Rows.Count).End(xlUp))
Me.ChartObjects("Chart 1").Chart.SetSourceData Source:=chrtdata
End With
End If
End Sub
Regards
http://www.get-digital-help.com/2013/07/03/use-drop-down-lists-to-compare-data-series-in-an-excel-chart/