Run Time Error 91 - Object variable or With block variable not set when using Pie Chart

My Code below:
Sub PieSourceData()

Sheets("ReportSummary").ChartObjects("Chart 5").Activate

Sheets("DataSheet").Select
ActiveChart.SetSourceData Source:=Range("A245:B249")


End Sub

It is failing at the line :ActiveChart.SetSourceData Source:=Range("A245:B249")

Thanks in advance.