Helper list - bool type not work together with callback

[SupuS]

Hi,

I would like to modify admin order list. I use this code for display column:

'test' => array(
                'title' => $this->l('Test'),
                'type' => 'bool',
                'orderby' => false,
                'havingFilter' => false,
                'remove_onclick' => true,
                'callback' => 'forTest',
                'icon' => array(
                    1 => array(
                        'src' => 'test.png',
                        'alt' => $this->l('Alt test'),
                    )
                ),
            ),

and this function:

public function forTest($test, $tr)
{
  return true;
}

But the column contains value "1" instead of icon. When I remove calback function with using value from db select than icon is showed correctly. Is there a way to use bool, callback and icon together?

Thanks for any idea.