This almost always happens when you are unable to connect to the database from DNN.
Navigate to
http://localhost/DNN5/Install/install.aspx
and see if it throws a connection error just to be sure.
Is this a local database? If so try using (local)\InstanceName (I assume your instance name is DWYATTMSSQL) so (local)\DWYATTMSSQL
Also make sure that you have SQL authentication enabled in SQL server, instead of Windows Authentication only, which is the default for SQL installations.