I am using Visual Studio 2013 with .NET Framework 4.5.

I have included the `System.Configuration` as a reference in the project.

I have also included a using statement in the class as such:

```
using System.Configuration;

```

However, the following line still gives me the above subject error. How do I get rid of the error?

```
using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["WarrantySqlConnection"].ToString()))

```

The compile time error is on the `ConfigurationManager` word.