跟踪PHP代码中的语法错误

你能找到错误吗?我真的很感激。

我想是花括号，但我不知道在哪里。我这样做是为了呼应他们个人资料中的用户名。例如<? echo $username; ?>，我没有测试回显，因为我得到一个语法错误。

     <?php
        // check for errors
        error_reporting(E_ALL);
        ini_set('display_errors', True);
        // deny access if not logged
        if (!session_id()) session_start();
        if (!$_SESSION['logon']){ 
            header("Location:login.php");
            die();
        }
        $username = $_POST['username'];  //martin
        $password = $_POST['password']; //123456
            if (isset($_POST['username'])) 
        {   
            // connect to server
            $con = mysql_connect("localhost", "root", "");
            if(!$con){
                die('Could not connect: '. mysql_error());}
            mysql_select_db("test", $con);
            if(mysql_num_rows(mysql_query("SELECT * FROM users where username = '$username' AND password = '$password'")))
{
         //Correct information
            $sql = "SELECT * FROM users where username = '$username' AND password = '$password'";
            $result = mysql_query($sql);
            if (!$result) {
               die('Invalid query: ' . mysql_error());
            }
            while($row = mysql_fetch_array($result))
            $expire = time()+60*60*24*30;//1 month
            setcookie("id", $row['id'], $expire);
            mysql_close($con);
            }
        ?>