You had two sub routines, but only one end:
Private Sub CommandButton20_Click()
ActiveSheet.ChartObjects("Chart 60").Activate
ActiveChart.ChartType = xlLine
End Sub
Works for me.
You can also assign a macro to a chart so something like:
Sub ChangeMe()
ActiveSheet.ChartObjects("Chart 60").Activate
If ActiveChart.ChartType = xlLine Then
ActiveChart.ChartType = xlBarClustered
Else
ActiveChart.ChartType = xlLine
End If
End Sub
might be worth investigating.