dequeue problem

Here is my code i got it from Oracle PL/SQL Prog. Book. i am getting the error when i am trying to execute the stored procedure.
I would like to know what is the error in this sp.
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CREATE OR REPLACE PROCEDURE sp_clear_Q(p_QueueName IN VARCHAR2)
AS
v_error_num number;
v_message concerned;

v_dequeue_options dbms_aq.dequeue_options_t;
v_message_properties dbms_aq.message_properties_t;
v_message_handle RAW(16);

e_QTimeOut EXCEPTION;
PRAGMA EXCEPTION_INIT(e_QTimeOut, -25254);
BEGIN
BEGIN
-- Set Dequeue Options
v_dequeue_options.consumer_name := 'SYNCMIN';
v_dequeue_options.dequeue_mode := DBMS_AQ.REMOVE;
v_dequeue_options.visibility := DBMS_AQ.ON_COMMIT;
v_message_properties.delay := DBMS_AQ.NO_DELAY;

LOOP
v_dequeue_options.wait := 0;
DBMS_OUTPUT.PUT_LINE ('Befor Dequeue ...');
DBMS_AQ.DEQUEUE(
queue_name =>'SYNCMIN.tdma_concerned_q',
dequeue_options => v_dequeue_options,
message_properties => v_message_properties,
payload => v_message,
msgid => v_message_handle);
END LOOP;
EXCEPTION
WHEN e_QTimeOut THEN
NULL;
END;

-- Commit all dequeue.
COMMIT;
END;
===================================================

=====================================================
SQL> execute sp_clear_q('');
BEGIN sp_clear_q(''); END;

*
ERROR at line 1:
ORA-21000: error number argument to raise_application_error of -600 is out of
range
ORA-06512: at "SYNCMIN.SP_CLEAR_Q", line 46
ORA-06512: at line 1
====================================================
Thanks.