Access Denied using ASP.NET Identity + Facebook Test Users

I am developing an ASP.NET MVC 5 website with facebook external login. Everything works fine with my fb account and other real fb accounts.

Now i am trying to use the Test Users Facebook features like described this http://ift.tt/1NsUzjO

[AllowAnonymous]
public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
{
    var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
    if (loginInfo == null)
    {
         return RedirectToAction("Login");
    }

I didn't change the ASP.NET template code because, with facebook real accounts, it works well without any changes. With Facebook Test Users the variable loginInfo is null and analyzing the web request with Fiddler i read Access Denied in the URL (I accepted Facebook permissions as usual).