Error: Invalid value passed to append; please use appendMeta()

#0 /home/v/vbrestecom/public_html/library/Zend/View/Helper/HeadMeta.php(160): Zend_View_Helper_HeadMeta->append(Object(stdClass))
#1 [internal function]: Zend_View_Helper_HeadMeta->__call('appendName', Array)
#2 /home/v/vbrestecom/public_html/application/views/scripts/subcategory/view.phtml(8): Zend_View_Helper_HeadMeta->appendName('keywords', NULL)
#3 /home/v/vbrestecom/public_html/library/Zend/View.php(107): include('/home/v/vbreste...')
#4 /home/v/vbrestecom/public_html/library/Zend/View/Abstract.php(787): Zend_View->_run('/home/v/vbreste...')
#5 /home/v/vbrestecom/public_html/library/Zend/Controller/Action/Helper/ViewRenderer.php(902): Zend_View_Abstract->render('subcategory/vie...')
#6 /home/v/vbrestecom/public_html/library/Zend/Controller/Action/Helper/ViewRenderer.php(923): Zend_Controller_Action_Helper_ViewRenderer->renderScript('subcategory/vie...', NULL)
#7 /home/v/vbrestecom/public_html/library/Zend/Controller/Action/Helper/ViewRenderer.php(962): Zend_Controller_Action_Helper_ViewRenderer->render()
#8 /home/v/vbrestecom/public_html/library/Zend/Controller/Action/HelperBroker.php(276): Zend_Controller_Action_Helper_ViewRenderer->postDispatch()
#9 /home/v/vbrestecom/public_html/library/Zend/Controller/Action.php(513): Zend_Controller_Action_HelperBroker->notifyPostDispatch()
#10 /home/v/vbrestecom/public_html/library/Zend/Controller/Dispatcher/Standard.php(285): Zend_Controller_Action->dispatch('viewAction')
#11 /home/v/vbrestecom/public_html/library/Zend/Controller/Front.php(934): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#12 /home/v/vbrestecom/public_html/application/bootstrap.php(661): Zend_Controller_Front->dispatch()
#13 /home/v/vbrestecom/public_html/index.php(17): Bootstrap->runApp()
#14 {main}