Can not create capture, ORA-02049: timeout: distributed transaction waiting for lock

Dear All,

I want to create downstream database.

When I try to create capture at stream database, it show message as below:

 SQL> exec  DBMS_CAPTURE_ADM.CREATE_CAPTURE(queue_name => 'DOWNSTREAM_CAPTURE_Q',capture_name => 'DOWNSTREAM_CAPTURE_Q',rule_set_name => NULL, start_scn  => NULL, source_database  => 'ELTITX', use_database_link  => true, first_scn => NULL,logfile_assignment => 'implicit');

BEGIN DBMS_CAPTURE_ADM.CREATE_CAPTURE(queue_name => 'DOWNSTREAM_CAPTURE_Q',capture_name => 'DOWNSTREAM_CAPTURE_Q',rule_set_name => NULL, start_scn  => NULL, source_database  => 'ELTITX', use_database_link  => true, first_scn => NULL,logfile_assignment => 'implicit'); END;

*

ERROR at line 1:

ORA-02049: timeout: distributed transaction waiting for lock