Cannot modify header information - headers already sent

Hi! I'm using CodeIgniter for quite awhile now..and I'm currently facing an error

Code:

A PHP Error was encountered

Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at /project/system/core/Exceptions.php:271)

Filename: helpers/url_helper.php

Line Number: 564

Backtrace:

File: /project/application/core/MY_Controller.php
Line: 75
Function: redirect

File: /project/application/controllers/User.php
Line: 116
Function: user_view

This is Line 75 of My_Controller

PHP Code:

if( ! $this->session->email || $this->session->email == NULL || $this->session->isLoggedIn !== TRUE) {
     $this->session->sess_destroy();
     redirect(site_url('login'));
}  


just incase this is needed, I used echo in my User controller because this is where I get some ajax request.

Thank you very much

UPDATE:

I just found out that this one might be the one causing problem.

PHP Code:

$data['pending_count']   = ($pending->count * $pending->pages);
$data['paid_count']      = ($paid->count * $paid->pages);
$data['cancelled_count'] = ($cancelled->count * $cancelled->pages); 


I cannot use redirect(site_url('login')); below this code. But if I put redirect before $data[] it works just fine.

Is there any way I can solve my error? Thank you!

You get the headers already sent error because you have written to the output already.

Which is most Lilly what the $data is doing. So yes you would need to redirect before
you write the $data to the view.

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )