this code supposed to wrtie how many mails i have in my mailbox in
gmail:

<?php
$ServerName = "{pop.gmail.com:995/pop3/ssl/novalidate-cert}";

$UserName = "user";
$PassWord = "pass";

$mbox = imap_open($ServerName, $UserName,$PassWord) or die("Could
not open Mailbox - try again later!");

if ($hdr = imap_check($mbox)) {
echo "Num Messages " . $hdr->Nmsgs;
} else {
echo "failed";
?>

when i used this code at the first time,it wrote exacly how many mail
i have,but every time when i used it again its wrote one mail less.
what the problem??