Joel: I did what you suggested, and commented the NAMES.DEFAULT_DOMAIN on my current server, so that both servers are the same. But I still got the same error.
Then I tried to link to another remote database, and it worked. I do find that my current and remote database (the one that works) both have similar but maybe wrong global_name:
select * From global_name;
I got 'OOGF.US.ORACLE.COM' on current server,
and 'OOHB.US.ORACLE.COM' on the remote server.
while as said previously, I got 'OGRE' on the remote server that refuses to link.
Any inputs? Is it right to have global_name with 'US.ORACLE.COM' as suffix, even though you are certainly not in that domain? Which config file should I check for this parameter? Thanks a lot. Changsong