我正在安装Amasty一页结帐，以替换当前（糟糕）的一页结帐扩展。我收到以下错误：
Invalid method Mage_Customer_Block_Form_Login::addItemRender(Array
(
[0] => bundle
[1] => bundle/checkout_cart_item_renderer
[2] => checkout/cart/sidebar/default.phtml
)
)
#0 [internal function]: Varien_Object->__call('addItemRender', Array)
#1 [internal function]: Mage_Customer_Block_Form_Login->addItemRender('bundle', 'bundle/checkout...', 'checkout/cart/s...')
#2 /app/public/app/code/core/Mage/Core/Model/Layout.php(348): call_user_func_array(Array, Array)
#3 /app/public/app/code/core/Mage/Core/Model/Layout.php(214): Mage_Core_Model_Layout->_generateAction(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_Layout_Element))
#4 /app/public/app/code/core/Mage/Core/Model/Layout.php(210): Mage_Core_Model_Layout->generateBlocks(Object(Mage_Core_Model_Layout_Element))
#5 /app/public/app/code/local/Amasty/Scheckout/Helper/Data.php(992): Mage_Core_Model_Layout->generateBlocks()
#6 /app/public/app/code/local/Amasty/Scheckout/Model/Observer.php(251): Amasty_Scheckout_Helper_Data->getLayoutHtml('checkout_onepag...')
#7 /app/public/app/code/local/Amasty/Scheckout/Model/Observer.php(94): Amasty_Scheckout_Model_Observer->_prepareOnepageShippingMethodHtml(Object(Varien_Object))
#8 /app/public/app/code/core/Mage/Core/Model/App.php(1358): Amasty_Scheckout_Model_Observer->handleBlockOutput(Object(Varien_Event_Observer))
#9 /app/public/app/code/core/Mage/Core/Model/App.php(1337): Mage_Core_Model_App->_callObserverMethod(Object(Amasty_Scheckout_Model_Observer), 'handleBlockOutp...', Object(Varien_Event_Observer))
#10 /app/public/app/Mage.php(456): Mage_Core_Model_App->dispatchEvent('core_block_abst...', Array)
#11 /app/public/app/code/core/Mage/Core/Block/Abstract.php(947): Mage::dispatchEvent('core_block_abst...', Array)
#12 /app/public/app/code/core/Mage/Core/Block/Abstract.php(641): Mage_Core_Block_Abstract->toHtml()
#13 /app/public/app/code/core/Mage/Core/Block/Abstract.php(585): Mage_Core_Block_Abstract->_getChildHtml('shipping_method', true)
#14 /app/public/app/design/frontend/base/default/template/amasty/amscheckout/onepage.phtml(295): Mage_Core_Block_Abstract->getChildHtml('shipping_method')
#15 /app/public/app/code/core/Mage/Core/Block/Template.php(241): include('/app/public/app...')
#16 /app/public/app/code/core/Mage/Core/Block/Template.php(272): Mage_Core_Block_Template->fetchView('frontend/base/d...')
#17 /app/public/app/code/core/Mage/Core/Block/Template.php(286): Mage_Core_Block_Template->renderView()
#18 /app/public/app/code/core/Mage/Core/Block/Abstract.php(923): Mage_Core_Block_Template->_toHtml()
#19 /app/public/app/code/core/Mage/Core/Block/Text/List.php(43): Mage_Core_Block_Abstract->toHtml()
#20 /app/public/app/code/core/Mage/Core/Block/Abstract.php(923): Mage_Core_Block_Text_List->_toHtml()
#21 /app/public/app/code/core/Mage/Core/Block/Abstract.php(641): Mage_Core_Block_Abstract->toHtml()
#22 /app/public/app/code/core/Mage/Core/Block/Abstract.php(585): Mage_Core_Block_Abstract->_getChildHtml('content', true)
#23 /app/public/app/design/frontend/rwd/default/template/page/1column.phtml(55): Mage_Core_Block_Abstract->getChildHtml('content')
#24 /app/public/app/code/core/Mage/Core/Block/Template.php(241): include('/app/public/app...')
#25 /app/public/app/code/core/Mage/Core/Block/Template.php(272): Mage_Core_Block_Template->fetchView('frontend/rwd/de...')
#26 /app/public/app/code/core/Mage/Core/Block/Template.php(286): Mage_Core_Block_Template->renderView()
#27 /app/public/app/code/core/Mage/Core/Block/Abstract.php(923): Mage_Core_Block_Template->_toHtml()
#28 /app/public/app/code/core/Mage/Core/Model/Layout.php(555): Mage_Core_Block_Abstract->toHtml()
#29 /app/public/app/code/core/Mage/Core/Controller/Varien/Action.php(390): Mage_Core_Model_Layout->getOutput()
#30 /app/public/app/code/local/Amasty/Scheckout/controllers/Rewrite/OnepageController.php(48): Mage_Core_Controller_Varien_Action->renderLayout()
#31 /app/public/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Amasty_Scheckout_Rewrite_OnepageController->indexAction()
#32 /app/public/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('index')
#33 /app/public/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#34 /app/public/app/code/core/Mage/Core/Model/App.php(365): Mage_Core_Controller_Varien_Front->dispatch()
#35 /app/public/app/Mage.php(692): Mage_Core_Model_App->run(Array)
#36 /app/public/index.php(124): Mage::run('', 'store')
#37 {main}
有人会提出任何建议吗？