ช่วยหน่อยครับ login ด้วย password_verify จากdatabase ไม่ผ่าน

class employee extends db
{
        private $user;
        private $pass;
        private $fname;
        private $lname;
        private $id;
        private $phone;
        private $pic;
        private $bd;
        private $pos;
        public function insert($user, $pass, $fname, $lname, $bd, $phone, $pic, $pos)
        {
                $create = date("Y-m-d");
                $passEncode = password_hash($pass, PASSWORD_DEFAULT);
                $stmt = $this->conn()->prepare("INSERT INTO employee (em_id,em_user,em_pass,em_fname,em_lname,em_bd,em_phone,em_pic,pos_id,em_create) 
        VALUE (NULL,'$user','$passEncode','$fname','$lname','$bd','$phone','$pic',$pos,$create)");
                $stmt->execute();
        }
        public function login($user, $pass)
        {
                $this->user = $user;
                $this->pass = $pass;
                $stmt = $this->conn()->prepare("SELECT * FROM employee WHERE em_user = ?");
                $stmt->bindParam(1,$this->user);
                $stmt->execute();
                while ( $row = $stmt->fetch()) {

                      if(password_verify($this->pass, $row['em_pass'])){
                        echo "ok";
                      }else{
                        echo "NO";
                      }
                }
        }
}
$user = new employee;
$user->login("admin","admin");