How to check if user is logged in - asp.net

Question

I have created a Login page where users must provide username and password to have access to some specific resources, where they can upload images, or just edit some description about themselves.
My web.config file looks like this:
<authentication mode="Forms">
<forms loginUrl="Secure/Login.aspx" defaultUrl="index.aspx" name=".ASPXFORMSAUTH" timeout="30"/>
</authentication>
<authorization>
<allow users="*"/>
</authorization>
</system.web>
<location path="Secure">
<system.web>
<authorization>
<deny users="?"/>
</authorization>
</system.web>
</location>
So when the user has typed in the username and pw, he is redirected to the index.aspx page.
Depending wether the user is logged in or not, the index.aspx should show or hide some stuff.
This is how I check if he is logged in:
bool isLoggedIn = HttpContext.Current.User.Identity.IsAuthenticated;
if (isLoggedIn)
{
placeHolder2.Visible = true;
...
}
Now the problem is that the: HttpContext.Current.User.Identity.IsAuthenticated; ALWAYS returns true, so unauthorised people will be seeing the stuff that should be hidden.
I am not sure about the: HttpContext.Current.User.Identity.IsAuthenticated;
I just googled "How to check if user is logged in", and suggestions were the:
HttpContext.Current.User.Identity.IsAuthenticated;
I want only the people that are logged in to view the private stuff. How do I go about this? How do I make the: HttpContext.Current.User.Identity.IsAuthenticated only return true when the user is logged in?
Thanks

Answer 1

if (Request.IsAuthenticated) {.....}
edit based on some comments
Authenticated via "Forms", check here
HttpContext.Current.User.Identity.IsAuthenticated // will be "Forms" if using forms based auth
// "Negotiate" is using windows integrated
// etc
If using .net 4.5 and you wanted "SET" user claims.
The ClaimsPrincipal is recommended reading

Answer 2

bool isLoggedIn = System.Web.HttpContext.Current.User.Identity.IsAuthenticated

Answer 3

My coding is
bool val1 = (System.Web.HttpContext.Current.User != null) &&
(System.Web.HttpContext.Current.User.Identity.IsAuthenticated) &&
(System.Web.HttpContext.Current.User.Identity.AuthenticationType.ToString() == "Forms");
for identifying the users with domain login and logged in form