Attaching Claims to the FormsIdentity in ASP.NET MVC

I am attempting to add custom claims to my FomsIdentity class instance after logging in through Forms Authentication in ASP.NET MVC. 
However, when I attempt to retrieve my Claims back from another controller, I am only getting a single Claim back stored with my FormsIdentity!
This is how I am attaching Claims:
private void SignIn(string userName, int expirationTime) { // Clear any lingering authentication data FormsAuthentication.SignOut(); //Create a new Forms Authentication Ticket FormsAuthenticationTicket newAuthTicket = new FormsAuthenticationTicket(userName, true, expirationTime); //Create the FormsIdentity object FormsIdentity formsIdentity = new FormsIdentity(newAuthTicket); List<Claim> claims = new List<Claim>(); claims.Add(new Claim(ClaimTypes.Name, userName)); claims.Add ...