compression problem and wrong MIMIC

[eluser]pistolPete[/eluser]
[quote author="Dennis_gull" date="1251816982"] any ideas why I get this error message?[/quote]

Just read the comment above the setting:

Code:

/* ...
| VERY IMPORTANT:  If you are getting a blank page when compression is enabled it
| means you are prematurely outputting something to your browser. It could
| even be a line of whitespace at the end of one of your scripts.  For
| compression to work, nothing can be sent before the output buffer is called
| by the output class.  Do not "echo" any values with compression enabled.
|
*/
$config['compress_output'] = TRUE;

You must use a view, don't echo from the controller.
You could use a very simple view like this:

ajax_view.php

Code:

<?php
echo $ajax_data;

ajax_controller.php

Code:

<?php
class Ajax_controller extends Controller {

    function some_function()
    {
        $data = array('ajax_data' => 'some data');
        $this->load->view('ajax_view', $data);
    }
}