Lock problem in online 5.0

hi I have a problem regarding the locking of rows in the database and I am not able to understand what is going on. Can anybody throw some light on it ? thanks nataraj ------------------------------------------------------- DATABASE set to unbuffered logging Locking mode: is default (row level locking ?). When the delete of the table is going on (the code below does it ), and if an insert into the table is made the following error is returned. Note: There is no begin and commit work enclosing the above delete. ISAM error -154:Could not insert new row into table. --------- code fragment ---------------------------------- $ SET LOCK MODE TO WAIT 45; /* Delete records * older than the number of days passed. */ for (hours=0; hours<24; ++hours) { sprintf (time_str, "%2d:59", hours); $ DELETE FROM opt WHERE logot <= CURRENT YEAR TO SECOND - :days UNITS DAY AND EXTEND (logot, HOUR to MINUTE) <= :time_str ; } --------------------TABLE ------------------------------------------- Column name Type Nulls op_id char(10) no logit datetime year to second no logot datetime year to second no totpg integer no chart integer no mesgln integer no admin integer no pin_no smallint yes -------------------------INDEX------------------------------------------ Index name Owner Type Cluster Columns 110_13 informix unique No op_id logit logot