MVC :: Securing Action From JQuery Call?

How to secure an Action filtered with Authorize method from a jQuery call? I have this Authorize filter and it work's cause users are redirected if not logged-in. But after logging-out then accessing previous open pages that needs authorization, they weren't redirected at all. This jQuery is initialize when a button is clicked,

jQuery.post(
"/controllername/IsUserActive", {
}, function (data) {
if (data){
$('#div_user_active').html(data);
{ else {
$('#div_user_active').html('Not Active');
}
}
);

then calls this Action method.

<Authorize()> _
Function IsUserActive() As Boolean
Return True '<<---this keeps returning even users are already logged-out.
End Function

Overall, I wanted ajax(jQuery) to update/read a portion of the page but gets redirected if not authorized.