How to add external login in .net web api 2?

Question

I am trying to add an external login with a template from MVC5, Web API2 using the method

Task<IHttpActionResult> AddExternalLogin(AddExternalLoginDTO model)

For this method, only one ExternalAccessToken parameter is needed - a token from FB, Google, ...

But the ticket for some user data is still zero

AuthenticationTicket ticket = AccessTokenFormat.Unprotect(model.ExternalAccessToken);

Where is the problem?