problem with imap_fetch_overview()

[mr_moggie]

there's these few lines in my script...
i was able to connect and list the mailboxes but whenever i try to use the imap_fetch_overview() or imap_headers() function... IE would response with a "Cannot find server" page and firefox will download a blank "script.php"...

did i do anything wrong with the script??

$mailbox = imap_open("{mail.example.com/imap:143}INBOX", "username", "password");
$mails = imap_fetch_overview($mailbox,"1:*", FT_UID);
var_dump($mails);
imap_close($mailbox);