now i am using oracle intermedia,oracle version si 8.1.7.4
i create a table ,the table have two column .one is (id number)
one is (snd ordsys.ordaudio).now i can import a audio file
from harddisk to database ,but when i export the audio file
from database to harddisk,i encounter problem

my export script
declare
obj ORDSYS.ORDAudio;
ctx RAW(4000) :=NULL;
begin
select snd into obj from sounds where id=1;
--- we export the sound into the table using a buffer (ctx).
if (obj.isLocal) then
obj.export(ctx, 'FILE', 'MYDIR', 'weiyi.mp3');
dbms_output.put_line('sound '||1||' exported');
else
dbms_output.put_line('sound cannot be exported since not stored locally in the database');
end if;
exception
when ORDSYS.ORDSourceExceptions.INCOMPLETE_SOURCE_INFOR MATION then
DBMS_OUTPUT.PUT_LINE('Export: value of srcType is NULL');
when ORDSYS.ORDSourceExceptions.METHOD_NOT_SUPPORTED then
DBMS_OUTPUT.PUT_LINE('Export: method not supported');
-- to see the complete errormessage for the source plugin exception,
-- you might remove the following exception handling for the source_plugin_exception
--when ORDSYS.ORDSOURCEExceptions.SOURCE_PLUGIN_EXCEPTION then
--DBMS_OUTPUT.PUT_LINE('Export: source plugin exception caught');
when ORDSYS.ORDSourceExceptions.IO_ERROR then
DBMS_OUTPUT.PUT_LINE('Export: problems writing BLOB data to the file specified');
when no_data_found then
dbms_output.put_line('no sound exist for number : '||1);
end;



the eorr information is

DECLARE
*
ERROR at line 1:
ORA-06510: PL/SQL: unhandled user-defined exception
ORA-06512: at "ORDSYS.ORDSOURCE", line 354
ORA-29540: class oracle/ord/media/source/OrdSourceSvr does not exist
ORA-06512: at "ORDSYS.ORDAUDIO", line 558
ORA-06512: at line 8


please tell my why!!!!!! i am very nervous now