jquery validation help needed

jquery validation help needed

I am using this jquery demo as my base to do form validation

http://jquery.bassistance.de/validate/demo/milk/

I am trying to check if a username already exists

here are some code snippets
RULE:
 username: {
                required: true,
                minlength: 6,
                remote: "includes/usernameCheck.php"
            },

MESSAGE:
username: {
                required: "Enter a username",
                minlength: jQuery.format("Enter at least {0} characters"),
                remote: jQuery.format("{0} is already in use")
            },

script inside usernameCheck.php

<?PHP

include "common.php";
include "functions.php";
$emails = array();
$sqlLogin = "select username from login;";
    $results = mysql_query($sqlLogin);
    while($row = mysql_fetch_row($results)){
        array_push($emails, $row[0]);
    }
   

$request = trim(strtolower($_REQUEST['email']));

$valid = 'true';
foreach($emails as $email) {
    if( strtolower($email) == $request )
        $valid = "The username: ".$request." has already taken.";
}
echo $valid;
?>

Can anyone explain why i would get a positive result. When i validate the field the message "Enter at least 6 characters" stays and never gets removed.

Here is a link to my form
http://www.visitmungo.com.au/register

thanks in advance
Ilan