Database link and ORA-12547

 am suddenly having a problem with a database link that used to work.here is the dblink DDL:

create datable link test

connect to {name} identified by {password}
using '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST={remote address})(PORT=1521)))
(CONNECT_DATA=(SID=XE)))';

I have a local machine running Oracle 10 xe on a windows xp box.  It had a existing link to a remote server that is accessed through a ipsec tunnel.  The remote machine is also Oracle 10 xe on a windows xp box.

When I attempt to use the dblink using SQL developer on the local machine logged into a local user using: select * from