oracle 10g 输出文件路径问题？

设置路径：create or replace directory dir_log as 'f:\log'; 
包程序如下：
create or replace package body LN_ASP_STAT_COMMON
as      
   para_date1        varchar2(8);
   procedure START_STAT(parameter_date in varchar2 default null)
as
    para_num                    number;    
    para_num1                   number;   
    para_curr_time              varchar2(10);
    para_reco_num               number;
    para_last_date              varchar2(10);
    para_start_date             varchar2(10);
    
    OutputFile                                                         UTL_FILE.FILE_TYPE;         --日志输出文件对象
          
          para_coustomer_no           varchar2(255);
          para_city                   varchar2(255);
          para_gonghao                varchar2(20);
          
          para_cityname               varchar2(255);
          para_last_name              varchar2(255);
    
begin
                if parameter_date is null then
                        para_date1:=to_char(sysdate-1,'yyyymmdd');
                else
                        para_date1:=parameter_date;
                end if;
                para_last_date := '20070202';
                
                para_start_date:=0;
                        
                --生成日志文件。保存在“/export/home3/pin/payment/log”目录下，文件名“balancelog_yyyymm.txt”  
                --DBMS_OUTPUT.PUT_LINE ('d://','balanceAPlog_'||para_date1||'.txt');
                --DBMS_OUTPUT.PUT_LINE ('d:\','balanceAPlog_'); 
                --OutputFile := UTL_FILE.FOPEN('FILEPATH','balanceAPlog_'||para_date1||'.txt','a');   
                OutputFile := UTL_FILE.FOPEN('dir_log','1.txt','a');
                UTL_FILE.PUTF(OutputFile,'%s        %s        %s\n','DATE','REMARK','LOG'); --写入文件,但内容保存在缓存中
                UTL_FILE.FFLUSH(OutputFile); --直接从缓存中写入文件 
                DBMS_OUTPUT.PUT_LINE (para_date1);
                        DBMS_OUTPUT.PUT_LINE (para_last_date);
                        while para_date1<para_last_date LOOP
      DBMS_OUTPUT.PUT_LINE (para_date1);
                        LN_ASP_STAT_CITYDEVELOP.START_STAT_CITYDEVELOP(para_date1);
                         
                        para_date1 := para_date1 + 1;
                  
           
         --输出操作到日志文件
                     UTL_FILE.PUTF(OutputFile,'%s        %s        %s\n',to_char(sysdate,'yyyymmdd hh24:mi:ss'),0,'##BEGIN to run balance_AP for '||para_date1); 
                     UTL_FILE.FFLUSH(OutputFile); 
       
                      <<Part1>> 
                                   null;         
                   END LOOP;
                 
                 --输出操作到日志文件，并关闭文件。
                UTL_FILE.PUTF(OutputFile,'%s        %s        %s\n',to_char(sysdate,'yyyymmdd hh24:mi:ss'),0,'##END to run balance_AP for '||para_date1); 
                UTL_FILE.FFLUSH(OutputFile);  
                UTL_FILE.fclose(OutputFile); end START_STAT;end LN_ASP_STAT_COMMON;
/
show errors;错误码如下
*
第 1 行出现错误:
ORA-29280: 目录路径无效
ORA-06512: 在 "SYS.UTL_FILE", line 33
ORA-06512: 在 "SYS.UTL_FILE", line 436
ORA-06512: 在 "ASP62.LN_ASP_STAT_COMMON", line 38
ORA-06512: 在 line 1请各位大侠看看什么地方有错误?多谢！