导出T_META_OBJECTTYPE数据遇到的问题

我们想导出T_META_OBJECTTYPE中的数据，使用此贴介绍的数据泵方法导出(https://vip.kingdee.com/article/285117969867333465) 执行成功但只导出了一个空的dmp文件，脚本如下，不知道哪里错了

DECLARE
h1 NUMBER;
BEGIN
h1 :=
DBMS_DATAPUMP.open (operation => 'EXPORT'
, job_mode => 'TABLE'
, job_name => 'JOB_N01' );
DBMS_DATAPUMP.
add_file (handle => h1
, filename => 'emp_objecttype20150511.log'
, directory => 'DATA_PUMP_DIR'
, filetype => 3);
DBMS_DATAPUMP.
add_file (handle => h1
, filename => 'emp_objecttype20150511.dmp'
, directory => 'DATA_PUMP_DIR'
, filetype => 1);

DBMS_DATAPUMP.
metadata_filter (handle => h1
, name => 'NAME_EXPR'
, VALUE => ' =''T_META_OBJECTTYPE'' '
, object_type => 'TABLE');

DBMS_DATAPUMP.start_job (h1);
DBMS_DATAPUMP.detach (h1);
END;