Ajax and CI

[eluser]Ajaxian64[/eluser]
Hy,
When I perform ajax on view where there is only html or php there is no problem
But when I introduce CI library or helper call inside the view then I get an error which says that the funtion is unknown.

in my contact controller:
function contact_form() {
$data['where']= 'contact_form_view';
if (IS_AJAX) {
$this->load->view('contact_form_view');
}
else {
$this->load->view('layouts/splash_layout',$data);
}
}
the ajax call is made on http://mywesite/contact/contact_form
And in my form view I have a <?php echo form_error('name'); ?> from form helper

Does someone know how to solve this ?

[eluser]Ajaxian64[/eluser]
Everythings works correctly.
was a mistake with is_ajax