Advanced Poll cookie

Warning: Cannot modify header information - headers already sent by (output started at /home/kszenica/public_html/index.php:2) in /home/kszenica/public_html/anketa1/poll_cookie.php on line 21

This warning always show when I voting.
What is problem?
Thanks

Make sure that the page your poll is embedded in has the
<?php require "poll_cookie.php"; ?>
tag before anything else. It must be at the very top of your page, before the <html> tag!

I had the same prob. To solve it, u must cut the include part before!! the html tag...then it'll works fine

I include this script before HTML tags
<?php
// Important! You have to include it before your html code
include_once "/home/cafferaf/public_html/cr_anketa/poll_cookie.php";
?>
but again i got warning every time when I voting.
I use version vith txt file as db

There must be nothing at all before the cookie include code, not even a space.