Help: TRANSACTION log and update

CASE: INFORMIX 5 database on SCO unix, database without transaction log I login server-1, from dbaccess trying to update a table on server-2 and get error "668: system command cannot be executed. 255: not in transaction." My SQL statement: UPDATE test@star0:assign set as_fname="Terry" WHERE as_ssnum="009999999" Question: This works if I directly logon server-2. But update from another server, it requires transaction log to be turned on. Is this what transaction log means to keep data integrity in a network environment? Thanks for help!