Dim checkbox1 As Boolean
Worksheets("sheet3").ChartObjects(3).Activate
ActiveChart.SeriesCollection(1).XValues = "=Sheet3!R3C1:R27C1"
If checkbox1 = True Then
ActiveChart.SeriesCollection(1).Values = "=Sheet3!R3C2:R27C2"
Else: ActiveChart.SeriesCollection(1).Values = "0"
ActiveChart.SeriesCollection(1).Name = "=Sheet3!R2C2"
ActiveChart.SeriesCollection(2).Values = "=Sheet3!R3C3:R27C3"
ActiveChart.SeriesCollection(2).Name = "=Sheet3!R2C3"
ActiveChart.Location Whe=xlLocationAsObject, Name:="Sheet3"
ActiveChart.HasDataTable = False
End If
End Sub

I have recorded most of the above code from a macro. The first line
(worksheets("sheet3") etc) generates an error and I haven't a clue what
the heck i am doing wrong now.

Second to this I have added in the If Else rows as I want a data series
only to appear if a checkbox is selected. Is this correct?