Entity Bean Transaction Isolation Level Problem

[hong]

I found that the transaction isolation set in my entity descriptor is
not working as expected. The isolation set is read commited. Problems
comes when two transaction one try to update the data x and then other
transaction read the changed data. The data read is supposed to wait
for the commit of the data update. but what I observed is not even
though I set the isolation level to read commited or even higher
repeatable read. then I think of the ejb entity bean caching behaviour
which is supposed to cache all the updated data and write to database
before the transaction is commited. I don't know whether EJB entity
bean could handle the data lock (Concurrency strategty: database) by
block the ejb_load once it found that other transaction is updating
the data. It seems that it is not the case. I tried to set the
delay-update-to-database-end-tx to false but still faces the same
problem.

I use sybase and weblogic 7. really apprepriate if someone could help.
Feel free to ask me question if there is anything I missed.

thousand thx
Hong