How do I get a subclass to listen to an event generated in a superclass?

I have a superclass, BasicPlot that generates an event 'DonePlotting' when the main plotting method is finished: notify(s, 'DonePlotting', event.EventData), where 's' is the object handle returned by the BasicPlot constructor.

A subclass FancyPlot < BasicPlot has a listener in its constructor that's supposed to be triggered by 'DonePlotting': s.hLsnr = addlistener(s, 'DonePlotting', 'PostSet', @(src, evt)fancyplot_event(s, src, evt));

However, when it gets to that line, Matlab reports, "The name 'DonePlotting' is not an accessible property for an instance of class 'FancyPlot'.

When I stop the program in the debugger just before the addlistener line and ask for 'events(s)', it lists 'DonePlotting'. Hum...

So, how do I get the subclass to listen to an event generated by the superclass?