Unable to connect SQL Server 2012
If you haven't verified that Named Pipes is enabled on the SQL instance, do this:
Open SQL Configuration Manager, usually found in Start > Microsoft SQL Server 2012 > Configuration Tools (in Server 2008/R2. If using Server 2012, just search for it with WinKey+S)
Go to SQL Server Network Configuration on the left. Open Protocols for .
Right-click Named Pipes if it's disabled (will be red) and choose Enable.

.Net seems to require named pipes (and your error above mentions it). There are probably other ways to connect that would not require this.