title: Where is System.Web.Security.MembershipProvider?
body: <p>I have a library project that should be the base for several web applications. I am trying to implement System.Web.Security.MembershipProvider but for some reason Visual Studio cannot find it. It manages to find System.Web.Security.SqlMembershipProvider but not MembershipProvider.</p>
  
  <p>Any idea why?</p>
  
  <p>I am using Visual Studio 2010 with .NET 4.</p>