Why dbms_metadata.get_ddl can not work for db link?

Question

db: 10.2.4
os: RH linux 5
our problem is that we can not get ddl from dbms_metadata.get_ddl for database link, however the db link does exist here as below.
SQL> select * from dba_db_links where owner='XXRPTH';
OWNER DB_LINK USERNAME HOST CREATED
XXR TO_DOPDB.XXR.COM TEST db_opdb 18-FEB-08
XXR XXRPTH_OPDBC.XXR.COM TEST db_opdb 15-JUL-08
XXR XXRPTH_BLIS.XXR.COM BLIS dbls 02-JUN-08
SQL> select dbms_metadata.get_ddl('DB_LINK','XXRPTH_OPDBC.XXR.COM','XXR') from dual;
ERROR:
ORA-31603: object "XXRPTH_OPDBC.XXR.COM" of type DB_LINK not found in schema "XXR"
ORA-06512: at "SYS.DBMS_SYS_ERROR", line 105
ORA-06512: at "SYS.DBMS_METADATA", line 2806
ORA-06512: at "SYS.DBMS_METADATA", line 4333
ORA-06512: at line 1
appreciate for any guides
thanks

Answer 1

I ran into this in a slightly different form, I can't remember all the rules and details, but to work around it I had to specify a fake name appendage in the db link creation in order to keep it from automatically appending the global domain.
Something like
create database link abcdef.remotealias connect to ... using 'remotealias'
rather than
create database link abcdef connect to... using 'remotealias'
At least I think it was fake, I was flopping around trying things until I got it to work, and I wound up making it the same as the tnsnames alias. I think I decided I didn't have to, but left it as the lesser of two confusions, and was miffed that the creation scripts I had been using for years suddenly had to be fixed. Yeah, it was my own damned fault, but I still think the way this works is crazy. Now hopefully someone will explain this simply so I look foolish.