To be able to make a connection to the MS SQL Server, the Microsoft SQL Server Native Client has to be available.
If you install the Isah Database Patch Engine on the database server, or on a computer containing an Isah 4.5 client, the Microsoft SQL Server Native Client is already installed.
The SQL Server Native Client version must match the SQL Server version: SQL Server Native Client 2008 R2 must be installed when you use SQL Server 2008. SQL Server Native Client 2012 must be installed when you use SQL Server 2012.