OPENDATASOURCE In Update Statement

Hi All

I'm trying to update feilds in a local table from a remote table using the following:
update schema.table1 set acc = r.acc, add = r.add
from OPENDATASOURCE('SQLOLEDB','Data Source=10.10.10.171;User ID=user;Password=mypw').db.schema.table1 as R, schema.table1 as L where R.acc = L.acc

When run from Query Analyser, it fails with:
Could not find server '"db"."schema"."table1" in sysservers. Execute sp_addlinkedserver to add the server to sysservers.

On both servers, the database, schema and table names are the same.

Running SQL2K SP4 on both servers. Don't want to set up linked servers, as they will only connect on a scheduled basis to perform updates.

Other queries such as insert work, as well as update OPENDATASOURCE( . . .) set x=L.x from schema.table where . . . so it's a prob with the From clause of the update.

Am I missing something, or is what I'm trying to do just not possible?

TIA