Strange problem with cookies in PHPPoll

I need help with cookies security in PHPPoll on my site:

http://nonameclan.net

IP security works fine, user with same IP can vote only once.

Cookie security don’t work and this is strange … Look:

http://elrom.pl/nnc/vote.php - this is my vote site, on this site everything working fine :/

I put it to my index.php on my main site (nonameclan.net) to the line:

<td class="sidelink" width="100%"><iframe name="ankieta" src="http://elrom.pl/nnc/vote.php" width="150" height="230" frameborder="0" scrolling="no"></iframe></td>

And now – cookies security on http://elrom.pl/nnc/vote.php site works properly but cookies protection on http://nonameclan.net (in file index.php) who has same site in a <iframe> doesn’t works.

I'v put this code at the beginning of my index.php file:

<?php

// Important! You have to include it before your html code

include_once "/home/users/elrom/public_html/nnc/votes/poll_cookie.php";

?>

<html>

<head>

So everything looks O.K. but cookies security don’t work ( if I turn off IP security u can refresh site and vote again or u can reconnect your connection, get new IP and revote again).

Thank’s for your help

Hans’