I don't know why I can't create users. Visual Studio 2012 ASP.NET Web Forms

[Rockfan]

I followed instructions from my Web Dev Class at University. So I opened the Web Site Admin Tool. I went an checked my provider config, and it seems to be okay. Then I tried to create users. But I got this: \[quote\] There is a problem with your selected data store. This can be caused by an invalid server name or credentials, or by insufficient permission. It can also be caused by the role manager feature not being enabled. Click the button below to be redirected to a page where you can choose a new data store. The following message may help in diagnosing the problem: Unable to connect to SQL Server database. Unable to connect to SQL Server database.\[/quote\]I don't know what else to do. I mean I know the the configuration at Web.Config is okay. The Connection is there: \[code\]<add name="DefaultConnection" providerName="System.Data.SqlClient" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=aspnet-SecurityPractice-20130407111315;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnet-SecurityPractice-20130407111315.mdf"/>\[/code\] I'm stuck. I don't know what to search for. I can't even browse my app_data folder for the mdf file because it's not there. I'm extremely confused. Our professor teaches us like we already know stuff about Visual Studio and so I don't understand a thing.