The free edition is limited to 4 layers per layout and a total of 100 events in your project.
I don't have the patience to wait 1 minute in zshare (you really should use DropBox
which is wait and add free). Still you can check in C2 in the status bar at the bottom (thanks Ashley who made me notice this not long ago) there is the total count of events.
If you try to edit an event (when you made too much layers or events), a warning window appears telling you the problem.
Make sure of the events count in your project.