how to save QOrganizerEventOccurrence?
I try
QOrganizerManager defaultManager;
QOrganizerEventOccurrence eventOccurrence;

eventOccurrence.setDisplayLabel("test");
eventOccurrence.setStartDateTime(QDateTime(QDate(2012, 3, 3)));
eventOccurrence.setEndDateTime (QDateTime(QDate(2012, 3, 4)));
eventOccurrence.setOriginalDate(QDate(2012, 3, 3));

defaultManager.saveItem(&eventOccurrence);

if (defaultManager.error())
qDebug() << defaultManager.error();

Result:
QOrganizerManager::InvalidOccurrenceError 15 The most recent operation failed because it was an attempt to save an occurrence without a correct InstanceOrigin detail