HTMLレポートの日付フォーマットが正しくないため、エラーが発生しましたORA-01861:文字とフォーマット文字列が一致しません

  PROCEDURE MAIN(ERRBUF        OUT VARCHAR2,
                 RETCODE       OUT VARCHAR2,
                 P_CUSTOMER_ID IN VARCHAR2,
                 P_PERSON_ID   IN VARCHAR2, 
                 P_MAKER_ID    IN VARCHAR2, 
                 P_START_DATE IN VARCHAR2, -- 
                 P_END_DATE   IN VARCHAR2 -- 
                 ) IS
  
    l_contract_date_from DATE; --  
    l_contract_date_to   DATE; --  
  BEGIN
    RETCODE              := '0';
    l_contract_date_from := trunc(fnd_conc_date.string_to_date(P_START_DATE));-- 
    l_contract_date_to   := trunc(fnd_conc_date.string_to_date(P_END_DATE));-- 
    OUTPUT_DATA_HTML(P_CUSTOMER_ID, 
                     P_PERSON_ID, 
                     P_MAKER_ID, 
                     l_contract_date_from, -- 
                     l_contract_date_to -- 
                     );
  END;


 PROCEDURE output_data_html(P_CUSTOMER_ID IN VARCHAR2,
                            P_PERSON_ID   IN VARCHAR2,
                            P_MAKER_ID    IN VARCHAR2,
                            P_START_DATE  IN DATE, -- 
                            P_END_DATE    IN DATE -- 
                            ) IS
 BEGIN
 
   SELECT *
     FROM OE_ORDER_HEADERS_ALL OOH
    WHERE (p_start_date IS NULL OR trunc(ooh.ordered_date) >= p_start_date)
      AND (p_end_date IS NULL OR trunc(ooh.ordered_date) <= p_end_date);
 END;


--  FND_STANDARD_DATE