Table level locking problem

Hi,

I am using Ingres II on SunOS 5.6 processer is sparc , front end is
Visual Basic 6.0
There is a backend procedure running in database which first deletes
the data and then inserts the data into a table from a temp table. i
hav specified a exclusive lock for this purpose
EXEC SQL SET LOCKMODE ON <table_name> WHERE LEVEL = TABLE,
READLOCK = EXCLUSIVE;

This lock is specified before the delete and only after inserts the
commit is fired.which in turn releases the locks from the table
The problem i am facing is that from front end, the select query is
able to access the locked table and fetching the rows.
Although in database backend level, from another session the same
query is waiting for the locks to be released and shows the data only
after the commit is fired but from front end the query is not waiting.
Though in IPM the lock is shown as exclusive and level is table for
that particular table.
In environment variable ING_SYSTEM_SET "set lockmode session where
readlock = shared" is given and max locks = 80 given.
I want the front end to wait till the commit is fired for fetching the
data from the table which is not happening now.
am i missing something to stop the front end to access the table for
select during the deletes and inserts in the table.