SQL & PL/SQL

Hi,

i try to execute a procedure PL/SQl 9i.
This procedure should open Notepad executable by running an API Windows .

The result is :
-----------------
SQL> execute sp_test_os_command;
BEGIN sp_test_os_command; END;

*
ERREUR ligne 1 :
ORA-28595: Extproc agent : Invalid DLL Path
ORA-06512:   "INTERFACE.RUN_OS_COMMAND", ligne 0
ORA-06512:   "INTERFACE.SP_TEST_OS_COMMAND", ligne 4
ORA-06512: ligne 1

Can you help me, please !!!!!!!!!
My code :
-----------
create or replace library kernel32 is 'c:\winnt\system32\kernel32.dll';

CREATE OR REPLACE FUNCTION "INTERFACE"."RUN_OS_COMMAND" (cmd in
VARCHAR2, show in binary_integer default 0)
return binary_integer
as external library KERNEL32
name "WinExec"
language C;

CREATE OR REPLACE PROCEDURE "INTERFACE"."SP_TEST_OS_COMMAND" as
test binary_integer;
begin
test:=run_os_command('notepad.exe',2);
end;