register script wont check for used names

[notaloser]

the script wont check for used usernames, and if a username that is already used is entered, it still creates the user in the database... why?

<?PHP 
if($HTTP_POST_VARS['submit']) { 

if (mysql_connect("localhost","root","pas
s")  

    or die ("<div align=center><span class=text>Unable to connect to the database.  Try again later.</span></div>")) { 

mysql_select_db('root');  

} else  

    print "Couldn't connect!<br>"; 


if (!$username || !$userpass || !$confirmp || !$useremail) { 

echo '<div align=center><span class=text>You have not entered all the fields. Please go back and fix the missing fields.</span></div>'; 
exit; 

} Else if ($userpass != $confirmp) { 

echo '<div align=center><span class=text>Your passwords do not match</span></div>'; 
exit; 
// new part added
} Else if (($userpass==$confirmp) && $username!=="" && $useremail!=="") {

$result2 = mysql_query("SELECT user_name FROM users WHERE user_name='".$_POST['username']."'");
$nameexists = mysql_num_rows($result2);

if ($nameexists == 1) {
echo "<span class=text>Name exists already. Please create a new name.</span>";
} else {

mysql_query("INSERT INTO users (user_name, user_pass, user_email, user_aimaol, user_msn, user_icq, user_admin) VALUES ( '$username', '$userpass', '$useremail', '$useraimaol', '$usermsn', '$usericq', '$useradmin'  ) ") 
or die ("<div align=center><span class=text>Unable to create user.  Try again later.</span></div>"); 
header('Location: emailer.php');
} // end if
} // end elseif
//
} //end else
?>

and then my emailer doesnt work ehre
PHP:

<?PHP

$headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
$headers .= "Bcc: [email][e-mail][/email]\r\n";

$to = $useremail;

$message = "Thank you for registering with mysite.  Please make sure you follow the <a href='http://mysite.com/rules.php'>rules</a>.<br><br>Information registered with:<br><br>Username: ".$username."<br>Password: ".$password."<br>AIM/AOL: ".$useraimaol."<br>MSN: ".$usermsn."<br>ICQ: ".$usericq."<br><br>Please keep this email so you don't forget login information. Thanks."; 

$subject = "mysite Registration";

mail ($to, $subject, $message, $headers);


?> 

[bastien]

try changing this:

$result2 = mysql_query("SELECT user_name FROM users WHERE user_name='".$_POST['username']."'"); 
    $nameexists = mysql_num_rows($result2); 

if ($nameexists == 1) { 
echo "<span class=text>Name exists already. Please create a new name.</span>"; 
} else { 

to this:

$sql="SELECT user_name FROM users WHERE user_name='".$_POST['username']."'"

$result2 = mysql_query($sql) or die ("Can't connect because ".mysql_error()); 
    $nameexists = mysql_num_rows($result2); 

if ($nameexists == 1) { 
echo "<span class=text>Name exists already. Please create a new name.</span>"; 
} else { 

to see if there is an error with the sql being parsed...