IN this way checkbox is created
$is_conveyance_required = new Zend_Form_Element_Checkbox(FORM_CHECKBOX_PREFIX . 'is_conveyance_required', array());
$is_conveyance_required->addDecorators(array(
array('HtmlTag', array('tag' => 'label')),
array('Label', array('tag' => '')),
));
$is_conveyance_required->setValue(1);
$is_conveyance_required->setChecked( true );
$this->addElement($is_conveyance_required);
and how form populating
$personal_form->populate($personal_data);
But zend form not populating checkbox...
<input type="checkbox" value="1" id="chk_is_conveyance_required" name="chk_is_conveyance_required">

Here is $personal_data array img
$personal_datamust have key & value with same name of your checkboxFORM_CHECKBOX_PREFIXtoo in that.