SQL & PL/SQL

this is a procedure i created in order to read and write to a directory. i get this error messages i don't what i am doing wrong here can you help me.
the error messages include
1.the declaration of the type of this expression is incomplet e
2. PLS-00201: identifier 'FTP.T_STRING_TABLE' must be declared
3.PLS-00201: identifier 'FTP.LOGIN' must be declared
4. PLS-00201: identifier 'FTP.LOGOUT' must be declared

PROCEDURE SP_TESTOMG_SIG
AS

l_conn UTL_TCP.connection;
l_list ftp.t_string_table;
BEGIN
l_conn := ftp.login ('172.20.100.240', '21', 'ftpuser', 'ftppassword');
ftp.LIST (p_conn => l_conn, p_dir => '/xch/signatures', p_list => l_list);
ftp.LOGOUT (l_conn);

IF l_list.COUNT > 0
THEN
FOR i IN l_list.FIRST .. l_list.LAST
LOOP
DBMS_OUTPUT.put_line (i || ': ' || l_list (i));
END LOOP;
END IF;
END;

Edited by: kama021 on Jun 10, 2009 1:37 AM