generate a registration id and display it after successful registration

i am trying to develop a registration form where the user fill the form and submit it then the status and the id should be displayed.
i have used uniq_id function to generate a random id and with the help of this  reference id i can retrieve the actual ID and display it back to the user. But unfortunately i am successful with the first registration after the first registration it throws an error that
 

Error:  "Warning: mysql_result(): Unable to jump to row 0 on MySQL result index 9".

my code:

<?php
include(conn.php);
$id = $_GET['id'];
$adv = $_GET['adv'];
$name = $_GET['name'];
$address = $_GET['address'];
$pincode = $_GET['pincode'];
$email = $_GET['email'];
$fax = $_GET['fax'];
$mobile = $_GET['mobile'];
$amount = $_GET['amount'];
$ddchno = $_GET['ddchno'];
$bank = $_GET['bank'];

$register = mysql_query( "insert into exbadv ( refid,adv,name,address,pincode,email,fax,mobile,amount,ddchno,bank) 
            values ('$id','$adv','$name','$address','$pincode','$email','$fax','$mobile','$amount','$ddchno','$bank')");

$id = $_GET['id'];
$result = mysql_query("SELECT id FROM exbadv WHERE refid = '$id'");
echo 'Your Registration id is ';echo mysql_result($result,0);
?>

Plz help me out,thank u.