At first it did not appear that the app was picking up my calendars at all, so it would not save or send. But after a couple of hours it finally showed both my default and birthday calendars and now it works like a charm! My wife had the same problem. Now we can bump events from phone to phone or send several events by email to each other without having to use the "invite" feature of Outlook. Love it! Four stars because there is no explanation about waiting for the calendars to appear and no help readily available.
LEAD360 about ShareCal - Easy Calendar Event Sharing via Email, iMessage and AirDrop