I use datapump on my database and it stop when processing SEQUENCE for a long time[more than half an hour] like this

expdp tmavote/MBR123 DIRECTORY=dmpdir DUMPFILE=test2.dmp

Export: Release 10.1.0.3.0 - Production on Tuesday, 13 May, 2008 11:51

Copyright (c) 2003, Oracle. All rights reserved.

Connected to: Oracle Database 10g Enterprise Edition Release 10.1.0.3.0 - Production
With the Partitioning, OLAP and Data Mining options
FLASHBACK automatically enabled to preserve database integrity.
Starting "TMAVOTE"."SYS_EXPORT_SCHEMA_12": tmavote/******** DIRECTORY=dmpdir DUMPFILE=test2.dmp
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 12.5 MB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/SE_PRE_SCHEMA_PROCOBJACT/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE

then I go Ctrl+c and exit
then export.log show me this error

;;; Export> exit
ORA-39125: Worker unexpected fatal error in KUPW$WORKER.UNLOAD_METADATA while calling DBMS_METADATA.FETCH_XML_CLOB [SEQUENCE:"TMAVOTE"."ROSEMSG2"]
ORA-04021: timeout occurred while waiting to lock object
----- PL/SQL Call Stack -----
object line object
handle number name
0x5eed0148 13460 package body SYS.KUPW$WORKER
0x5eed0148 5810 package body SYS.KUPW$WORKER
0x5eed0148 2034 package body SYS.KUPW$WORKER
0x5eed0148 6325 package body SYS.KUPW$WORKER
0x5eed0148 1208 package body SYS.KUPW$WORKER
0x5d5e3860 2 anonymous block
Job "TMAVOTE"."SYS_EXPORT_SCHEMA_11" stopped due to fatal error

note that ROSEMSG2 is a sequence. but if i run
expdp tmavote/MBR123 DIRECTORY=dmpdir DUMPFILE=test2.dmp TABLES=roseuser
expdp tmavote/MBR123 DIRECTORY=dmpdir DUMPFILE=test2.dmp INCLUDE=SEQUENCE:LIKE'ROSEMSG%'
both is working fine.

I'm new to oracle. How do i fix this??