using Microsoft.IdentityModel.Claims; fails in my Home controller!

I'm following the Microsoft guide for implementing federated identities. As it doesn't state where the code should be placed I created a file \App_Code\Auth.cs for it. when it's time to implement the FederationResult to my home controller I try to use the aforementioned namespace but VS complains of missing an assembly reference.

The weird thing is that the code in Auth.cs doesn't complain... 开发者_StackOverflowI've looked in the References item of the project and don't see anything I can recognise, although I did "Add STS reference" to the project. I've also looked in NuGet but don't see anything I should add...

what's going on here?

hmm... seems I just needed to add the reference manually. I don't know how come the assembly is available to some pieces of the code and not to others but it works!

One more thing, I needed to use Microsoft.IdentityModel.Web not .Claims