For completeness for others viewing this thread, the maximum version of SQL that DS6.9SP4 supports[1] is SQL Server 2012
http://www.symantec.com/business/support/index?page=content&id=DOC7340
When installing SQL Server my tip is to make sure it's open to TCP/IP connections on 1433. Before installing DS, I always fire up SQL Server Management Studio to make sure I can make a connection to the database services. If SQL Server Management Studio can't find the SQL instance, you can be certain that DS won't either.
Kind Regards,
Ian/.
[1] 'Supports' is a funny word. You often find that applications will work fine on higher SQL versions than the vendor has ratified them for. It's sometimes just a case of giving it a go. But just be aware that if you get niggles you're officially outside the application's support matrix.