Why can't I log into SQL Server using Windows Integrated Security?

Question

I'm trying to write a small app that will log into SQL Server to perform some admin functions. When I connect to SQL Server using the following connection string, I can log in fine:

Data Source=Localhost\SqlExpress;Initial Catalog=PeteDb;User Id=sa;Password=test; 

However when I want to use integrated:

Data Source=Localhost\SqlExpress;Integrated Security=True;MultipleActiveResultSets=True" 

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

How can this be solved? I am in the list of logins.

Answer 1

Do you need to specify the Initial catalog in the 2nd connection string? Something like this:

Data Source=Localhost\SqlExpress;Initial Catalog=PeteDb;Integrated Security=True; 

Answer 2

Had the same issue setting up and instance of SQL Server. This tutorial worked for me.