Codeigniter, not echoing validation_error(); - php

Question

I created a new controller questions.php which is not the default controller. I have already loaded the form_validation library but it did not echo out the validation errors when I submitted empty fields from my form. Other questions in SO seems to be completely unrelated to my situation.
Below is my questions.php controller. BTW I have only posted the necessary bits of the class controller.
<?php
class Questions extends CI_Controller{
function __construct() {
parent::__construct();
$this->load->helper(array('form'));
$this->load->library("form_validation");
}
public function user_logged_in(){
$this->load->library('../controllers/main');
$obj = new $this->main();
$status = $obj->logged_in();
if($status){
return true;
}else{
return false;
}
}
public function question_validation(){
if($this->user_logged_in() == false){
redirect('main/index');
} else{
$this->load->library('form_validation');
$this->form_validation->set_rules('input_title','Title','required');
$this->form_validation->set_rules('message','Question Details','required');
$this->form_validation->set_rules('vidya','Tags','required');
if($this->form_validation->run() == false){
$this->load->library('../controllers/main');
$obj = new $this->main();
$getUserData = $obj->getLogged_userData();
$userdata = array(
'uservalues' => $getUserData
);
$this->load->view('view_header');
$this->load->view('view_nav',$userdata);
$this->load->view('log_user/user_second_nav');
$this->load->view('question_posts/post_questions');
$this->load->view('view_footer');
} else{
echo "form has been submitted";
}
}
}
?>
The form page in view called post_questions.php which is shown below,
<?php
$this->load->helper("form");
echo validation_errors();
echo form_open('questions/question_validation');
?>
<p><h2>Question title</h2></p>
<p><input type="text" name="input_title" id="input_title"
placeholder="what is your question please be specific and clear"></p>
<p><h3>Now Describe in detail!</h3>
<p><textarea id="message" name="message" rows="10px" cols="86px"></textarea></p>
<p><h3>Tags</h3></p><p><input type="text" id="vidyagames" name="vidya"></p>
<p><input type="submit" name="post" value="Submit"></p>
</form>
Before this, the questions controller was giving me error like undefined property Questions::$form_validation so I added a __construct() and now it wont echo out the form validation errors.
Can you help me because probably the form isn't being submitted at all.
Thank You in Advance.