调用未定义的函数form_open（）？

My problem is that I am getting errors on CI's common function. I have done everything like:

 $autoload['helpers'] = array('form','myhelper');

Previously I am using Dreamweaver and not getting those messages there, now I have to work upon PhpStorm.

This is my default controller:

      $this->load->helper('url');
      $this->load->view('header');
      $this->load->view('home');
      $this->load->helper('form');
      $this->load->view('footer');

I have also used this tutorial, but no success.

These were the errors what i used to get!

Do not forget exteding CI_Controller like following:

application/controllers/Homepage.php

class Homepage extends CI_Controller 
{
    function __construct()
    {
        parent::__construct();
    }
}