PDO插入不正常

Question

当我登录时，假设插入，但没有做任何事情..在我的注册php上它将数据插入帐户，但是当我将数据插入在线时，它将无法工作.. PS-我是PDO的新手所以我不知道我做错了什么

<?php
session_start();
if(isset($_SESSION['users']) != ""){
echo '<script type="text/javascript">','index();','</script>';
}

include('../php/dbConnect.php');
    $username = $_POST['username'];
	  $password = $_POST['password'];

    $query = 'SELECT * FROM `accounts` WHERE username = ?';
    $queryprepare = $conn->prepare($query);
    $queryprepare->bindParam(1, $username, PDO::PARAM_STR);
    $queryprepare->execute();

    $row = $queryprepare->fetch();
    if($row['password'] == md5($password))
    {
      $_SESSION['online'] = true;
      $_SESSION['users'] = $username;
      $_SESSION['userid'] = $row['id'];
      $_SESSION['name'] = $row['name'];
      $_SESSION['age'] = $row['age'];
      $_SESSION['image'] = $row['image'];

      $check_row = 'SELECT * FROM `online` WHERE username = ?';
      $check_row_fetch = $conn->prepare($check_row);
      $check_row_fetch->bindParam(1, $username, PDO::PARAM_STR);
      $check_row_fetch->execute();

      $number_of_rows = $check_row_fetch->rowCount();
      if($number_of_rows != 0) {
        echo '<script type="text/javascript">','redirect();','</script>';
      }
      else{
        $online_insert = 'INSERT INTO online (username, name, age, image) VALUES (?, ?, ?, ?)';
        $online_insert_fetch = $conn->prepare($online_insert);
        $online_insert_fetch->bindParam(1, $SESSION['users'], PDO::PARAM_STR);
        $online_insert_fetch->bindParam(2, $SESSION['name'], PDO::PARAM_STR);
        $online_insert_fetch->bindParam(3, $SESSION['age'], PDO::PARAM_STR);
        $online_insert_fetch->bindParam(4, $SESSION['image'], PDO::PARAM_STR);
        $online_insert_fetch->execute();

          echo '<script type="text/javascript">','redirect();','</script>';
      }
    }
    else{
        echo("Wrong Credentials");
	}
?>