无法获得facebook用户age_range的公共价值

Question

我遇到了从我的MVC网络应用程序中获取Facebook用户详细信息的问题。我想获取age_range值（它是公共值并包含在public_profile中）或user_birthday值，它只向应用程序管理员提供它的值。

var x = new FacebookAuthenticationOptions();
            x.Scope.Add("user_birthday");
            x.Scope.Add("email");
            x.Scope.Add("public_profile");
            x.Scope.Add("user_friends");
            x.Scope.Add("age_range");

            x.AppId = "....";
            x.AppSecret = "....";
            x.Provider = new FacebookAuthenticationProvider()
            {
                OnAuthenticated = async context =>
                {
                    context.Identity.AddClaim(new System.Security.Claims.Claim("FacebookAccessToken", context.AccessToken));
                    foreach (var claim in context.User)
                    {
                        var claimType = string.Format("urn:facebook:{0}", claim.Key);
                        string claimValue = claim.Value.ToString();
                        if (!context.Identity.HasClaim(claimType, claimValue))
                            context.Identity.AddClaim(new System.Security.Claims.Claim(claimType, claimValue, "XmlSchemaString", "Facebook"));
                    }
                }
            };

            x.SignInAsAuthenticationType = DefaultAuthenticationTypes.ExternalCookie;
            app.UseFacebookAuthentication(x);

和另一个代码块，它正在抓取值。

var firstNameClaim = info.ExternalIdentity.Claims.First(c => c.Type == "urn:facebook:first_name");
                var lastNameClaim = info.ExternalIdentity.Claims.First(c => c.Type == "urn:facebook:last_name");
                var DOBClaim = info.ExternalIdentity.Claims.First(c => c.Type == "urn:facebook:birthday");
                var ageRange = info.ExternalIdentity.Claims.First(c => c.Type == "urn:facebook:age_range");

所以任何人都可以帮我抓住用户age_range值吗？