Sample Program dbrecs ARCHIVE doesn't work

I have been trying to implement incremental backup using the Lotus Domino C API functions with “Archive Transactional logging” enabled. Surprisingly, the sample program dbrecs.exe with “archive” argument ALWAYS RETURNS “No transaction log files are waiting to be archived.” even when I have commented out the call to NSFDoneArchivingLog. According to the documentation this call should not be done if you want to do repeated archiving of the same transaction log .TXN files.

Should the .TXN files fill up entirely (65MB) for this to work? My test server only has 15MB filled up according to “show stat database.rm.*”.

From what I understand we dont have to wait for the log to fill up to achieve periodic (say hourly) incremental archiving of the logs. So why no archive logs?