php script login problem -- please help!

members.php:

<?php
if (!isset($_COOKIE['loggedin'])) die("You are not logged in! Please <a href=login.html> login </a>");
$mysite_username = $HTTP_COOKIE_VARS["mysite_username"];
echo "you are logged in as $mysite_username.<p>";

?>

I always get the "you are not logged" in message. Here is the code that processes the login.
I have no problem matching the username with the password but somehow isset is always
returning 0 in members.php

setcookie("loggedin", "TRUE", time()+(3600 * 24));
setcookie("mysite_username", "$username");
echo "You are now logged in!<br>";
echo "Continue to the <a href=members.php>members</a> section.";

Thanks in advance,
Anand

Personally I would say use sessions, see the documentation on start_session unless you have specific reasons for using cookies.

Do you get any warnings, such as errors setting the cookie? Is your browser enabling cookies from your website (a privacy setting for most browsers)