Datapump full export error message ORA-22813

Hi,

When i try expdp (Full export) on 11GR1, i've got this error message :

Processing object type DATABASE_EXPORT/SCHEMA/TYPE/GRANT/OWNER_GRANT/OBJECT_GRANT

ORA-39126: Worker unexpected fatal error in KUPW$WORKER.UNLOAD_METADATA [OBJECT_GRANT:"USER1"]

ORA-22813: operand value exceeds system limits

And, in my trace file i have :

----- Error Stack Dump -----

ORA-22813: operand value exceeds system limits

----- Current SQL Statement for this session (sql_id=0b6x588m5jhfd) -----

SELECT /*+rule*/ SYS_XMLGEN(VALUE(KU$), XMLFORMAT.createFormat2('PROCACTSYS_T', '7')), 0 ,'SYSTEM' ,'PROCACT_SYSTEM' FROM SYS.KU$_PROCACT_SYS_VIEW KU$ WHERE KU$.PLSQL IS NOT NULL AND  KU$.PREPOST=0