error during page redirection
<p>when I redirect my page to another page <code>header("location:popup.php");</code> it gives following error -</p>

<p><strong>Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\303\levelupdate.php:289) in C:\xampp\htdocs\303\levelupdate.php on line 320</strong></p>
