CheckBox的问题

Question

I have the issue with the checkbox on zend_form when i get the value always i have 0 si my following code:

$e = new Zend_Form_Element_Checkbox('e');
    $e->setLabel('e');
    $emailnotification->options = array(
            'checked' => $e->getCheckedValue(),
            'unChecked' => $e->getUncheckedValue()
    );

and in controller:

$form->getValue('e')

when i inspect with firebug i find the hiden checkbox contains value 0 and checkbox value=1

Thanks in advance