php, session variable not passed

<?
// this is for login verification page

session_start(); // start session here
include "connection.php"; // connection file include for database
$username=$_REQUEST['username']; // username pass from username textbox
$password=$_REQUEST['password']; //password pass from password textbox
$sql="select * from tablename where username='$username' and password='$password'"; // query from registration table where user data is available
$result=mysql_query($sql);
mysql_num_rows($result);
if(mysql_num_rows($result)>0)
{
 $row=mysql_fetch_array($result);
 $_SESSION['id']=$row['id'];
 echo "<script>location.href='success.php'</script>"; // redirect the browser after successful login
 
}
else
{
 echo "<script>location.href='login.php?Err=Incorrect Username or Password'</script>"; // redirect the browser after invliad login or password insert
}

// end of the login verification page





// start of the each and every page you have to put up following information

session_start(); // start the session
$id=$_SESSION['id']; // this will carry the particular user's id

?>

Hi, Shashi,

Would you like to login into my web site server and have a look what is wrong. If yes, please send me an email or post your email address here, I will give you the username and password. Thanks,

My email: gloriabai@yahoo.com

Sincerely,

Gloria