Auditing Problem....

Hi All, I have started auditing on one informix server. When I use onaudit -n to start the new audit trail file, sometimes it creates a big file. I was expecting it to start with 0 bytes and gradually increasing. Can anybody tell me why it's happening like this ? Is it copying something from the previous file ? Is it related to transaction by any way ? My script is creating a new file and loading data from the old file into the database. I don't want to load duplicates in my next run. Please help. TIA Abhay.