IPN problem [website payments]

Hi, i searched on forums for similar problems, i found some threads but there isn't any good answer.
I tried to include paypal payments on my website, and i have problems with IPN file, i tried to buy something and paypal redirected me on my IPN page but it's blank.
I tried to enter on my IPN file without paypal checkout and it's blank.

Here is my IPN code :

<?php
// read the post from PayPal system and add 'cmd'

$req = 'cmd=_notify-validate';

foreach ($_POST as $key => $value) {
$value = urlencode(stripslashes($value));
$req .= "&$key=$value";
}

// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$fp = fsockopen ('www.paypal.com', 80, $errno, $errstr, 30);

// assign posted variables to local variables
$item_name = $_POST['item_name'];
$item_number = $_POST['item_number'];
$payment_status = $_POST['payment_status'];
$payment_amount = $_POST['mc_gross'];
$payment_currency = $_POST['mc_currency'];
$txn_id = $_POST['txn_id'];
$receiver_email = $_POST['receiver_email'];
$payer_email = $_POST['payer_email'];

if (!$fp) {
echo 'http error';
} else {
fputs ($fp, $header . $req);
while (!feof($fp)) {
$res = fgets ($fp, 1024);
if (strcmp ($res, "VERIFIED") == 0) {
if (eregi($payment_status ,"Completed")) {
echo "valid payment....";
}
}
else if(strcmp ($res, "INVALID") == 0) {
echo "invalid payment......";
}
}
}
fclose ($fp);
}
?>