[fw-mvc] Zend_Dojo_Form_Element_DateTextBox

Any idea why the DateTextBox only works when I add line 4?

1 $holiday = new Zend_Dojo_Form_Element_DateTextBox("holiday");
2 $holiday
3 ->setLabel('Holiday:')
4 ->setAttribs(array("dojoType"=>"dijit.form.DateTextBox"));
5
6 $this->addElements(array($holiday));