Plugin by name 'CompoundElement' was not found in the registry

[yaodong]

When use Xoops_Zend_Form_Element_Compound, the exception was threw :

Plugin by name 'CompoundElement' was not found in the registry; used paths: Zend_Form_Decorator_: Zend/Form/Decorator/

The PHP code :

        $form = new Xoops_Zend_Form();
        $buttons = new Xoops_Zend_Form_Element_Compound('form_buttons');

        $submitButton = new Zend_Form_Element_Submit( 'form_filter_submit');
        $submitButton->setLabel(XOOPS::_('Submit'));
        $buttons->addElement($submitButton);

        $resetButton = new Zend_Form_Element_Button('form_filter_reset');
        $resetButton->setLabel(XOOPS::_('Reset'));
        $buttons->addElement($resetButton);

        $form->addElement($buttons);