Problem with changing database logging mode

Hello, may be some of you had such kind of problem with administering Informix/on-line database: after turning logging off -> performing some operations on data -> turning logging on -> making level-0 archive -> database remain locked ? We are using Informix/on-line 7.10 on two sites: development and production. As you can guess this sequence works perfectly in development site, but in production site ... We have tried turning logging on and archiving with both "onarchive" and "ontape" utilities, on the * dbspaceset and on dbspace that contain desired database data and tried to do it several times, canceled changes (MODIFY/DBLOGGING.../CANCELCHANGE), etc. - all in all about 5 days were wasted. Now we have database which is "no log" or "locked". The only guess that it happends due to size of database - something like 2Gb. Probably, somebody of you had such kind of problems? If so, I will be appreciate for any advice. Best regards, Oleg Besedin