PHP Cookies Help

So, all this is new to me... but I am almost certain that I have this right.. however, it's not working

<?php
$Month = 2592000 + time(); //this adds 30 days to the current time
setcookie(warning, 1 , $Month); // sets cookie with name warning, value of 1, and expiry date
?>

<?php
if ($HTTP_cookie_VARS[warning] == "1")
{
echo "document.write('<javascript>showPopUp();</javascript>')"
}
else
{
 /*do nothing...*/
}
?>

PHP:

<script>showPopUp() {
tb_show('WARNING!', '{$mybb->settings['bburl']}/warning.html?width=250&height=300&modal=true');
}</script>

Code (markup):

Can anyone see where I am going wrong here?
What I want to happen is the the JavaScript to run only if in the cookie there is a value of 1.
(as the javascript is a warning pop up box, telling users they have to be 18+ to enter)

Thanks,
Jam

 

Maybe...

<?php
$Month = 2592000 + time(); //this adds 30 days to the current time
setcookie(warning, 1 , $Month); // sets cookie with name warning, value of 1, and expiry date
?>

<?php
if ($HTTP_cookie_VARS[warning] == "1") { 
	echo "document.write('<javascript>showPopUp();</javascript>')";
} else {
echo null; 
}
?>

Code (markup):

 

Thanks for your reply...
When I use the code that you provided, nothing still happen,and get this displaying on the screen:

So take it that there is something wrong with the echo statement?

Thanks,
Jam

 

try this

<?php
$Month = 2592000 + time(); //this adds 30 days to the current time
setcookie('warning', 1 , $Month); // sets cookie with name warning, value of 1, and expiry date
?>

<?php
if ($HTTP_cookie_VARS['warning'] == "1")
{
echo "document.write('<script type=\"text/javascript\">showPopUp();</script>')";
}
else
{
 /*do nothing...*/
}
?>

PHP:

 

echo "<script>showPopUp();</script>)"