Creating an SQL Server Workspace

I'm having some problems creating a connection to an MS SQL Server DB.

pWrkspcFact := CoSqlWorkspaceFactory.Create as IWorkspaceFactory ;
pProps := CoPropertySet.Create as IPropertySet ;
pProps.SetProperty ( 'DATABASE' , 'SamplesSQL' ) ;
pProps.SetProperty ( 'DBCLIENT' , 'SQLServer' ) ;
pProps.SetProperty ( 'SERVERINSTANCE' , 'Quandry' ) ;
pProps.SetProperty ( 'AUTHENTICATION_MODE' , 'OSA' ) ;
pWrkspcFact.Open( pProps , 0 ) ;

On calling Open I get along wait and the following error: "Failure to access the DBMS server"

This is coded in Delphi but it should work the same as .NET or C++. I've played with connection strings and different property names since the documentation is a bit inconsistent but without any success. Any idea what I'm missing or doing wrong?

Mitch Wolberg,
RockWare, Inc.