Php会话不起作用......任何人都可以告诉我我做错了什么

Question

Php会话不起作用......任何人都可以告诉我我做错了什么。

if (crypt($_POST["password"], $row["password"]) == $row["password"])
                        {
                            // remember that user's now logged in by storing user's ID in session
                            $_SESSION["id"] = $row["email"];
                            $_SESSION["firstname"] = $row["firstname"];
                            echo json_encode(array('auth' => 'true'));
                        }
                        else{
                           echo json_encode(array('auth' => 'false', 'error' => 'Invalid Username or Password'));
                        }