SQL & PL/SQL

Hi all,

i try to make a procedure to insert file into a column of blob type, it was success when i test the script in Oracle 9i environment, but when put it to 10G, will error like this:

ORA-22288: file or LOB operation FILEOPEN failed
Permission denied
ORA-06512: at "SYS.DBMS_LOB", line 523

directory is created and grant all permission to user.
create or replace directory DIR_BLOB as '/home/file_blob';

and use below command to read the file.
f_lob := bfilename('DIR_BLOB',v_input_name);
dbms_lob.fileopen(f_lob,dbms_lob.file_readonly);

it can detect file's existence and size, but fail when try to open.
i have confirmed with DBA that the directory is created both in OS & DB, and granted read&write permission to Oracle processes.

i google for several days, but can't find any solution for this.
could you kindly help on this?
many thanks!