Database connectivity pre-installation check fails
The pre-installation check reports that “Database connectivity” fails if it cannot detect the appropriate Microsoft SQL Server client software. To correct this issue, see Installing Database and Database Client Software to learn how to set up your back end database and client software.
If the pre-installation check still fails, check your path environment variable. For example, if you have installed the Microsoft SQL Server Express Edition client the path should contain:
C:\Program Files\Microsoft SQL Server\90\Tools\binn\