Paul - you need to use a four-part name... see below.
We normally "mask" our linked servers in a view then reference the view on the proc.
"OLE DB provider 'SQLOLEDB' does not contain table '"Customer"."dbo"."Cusfil"'."
from BOL -
After a linked server is defined, a four-part name in the form linked_server_name.catalog.schema.object_name can be used in Transact-SQL statements to reference data objects in that linked server. The table describes the parts of a four-part name.