If the event was added correctly the TGCalendarItem's ID property will be assigned.
If the insert failed you can review the log file to see if any errors have occurred. Logging can be enabled by setting Logging to true and LogLevel to llDetail.
The LOG file is generated automatically in your machine's Documents folder.
Thank you for quick reply. But I need a result of adding/update/delete operation (error number or error text) without analyzing log file after every insert. The result can be returned as an exception, as additional parameter or for example as LastErrorMessage member of TAdvGCalendar class. Could you repair/improve the component behaviour?