Maybe Informant doesn't handle the "intent" which is the mechanism for sending stuff between apps?
Please check with this app's developer. Here is what I use, it's all officially documented stuff:
Intent intent = new Intent(Intent.ACTION_INSERT, CalendarContract.Events.CONTENT_URI);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
intent.putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME, ...);
intent.putExtra(CalendarContract.EXTRA_EVENT_ALL_DAY, ...);
intent.putExtra(CalendarContract.EXTRA_EVENT_END_TIME, ...);
intent.putExtra(CalendarContract.Events.TITLE, subject);
intent.putExtra(CalendarContract.Events.DESCRIPTION, description);
try {
context.startActivity(intent);
...
The most important bit is:
Intent intent = new Intent(Intent.ACTION_INSERT, CalendarContract.Events.CONTENT_URI);
... and Informant may not be wired to respond to this.