Recoverable Error: Object of class Varien_Object could not be converted to string  in /chroot/home/boatstor/boatstore.com/html/app/code/local/Magalter/Banners/Model/Observer.php on line 21

#0 [internal function]: mageCoreErrorHandler(4096, 'Object of class...', '/chroot/home/bo...', 21, Array)
#1 /chroot/home/boatstor/boatstore.com/html/app/code/local/Magalter/Banners/Model/Observer.php(21): strlen('Object')
#2 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Core/Model/App.php(1338): Magalter_Banners_Model_Observer->generateBlocksAfter(Object(Varien_Event_Observer))
#3 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Core/Model/App.php(1317): Mage_Core_Model_App->_callObserverMethod(Object(Magalter_Banners_Model_Observer), 'generateBlocksA...', Object(Varien_Event_Observer))
#4 /chroot/home/boatstor/boatstore.com/html/app/Mage.php(448): Mage_Core_Model_App->dispatchEvent('controller_acti...', Array)
#5 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Core/Controller/Varien/Action.php(351): Mage::dispatchEvent('controller_acti...', Array)
#6 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Cms/Helper/Page.php(113): Mage_Core_Controller_Varien_Action->generateLayoutBlocks()
#7 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Cms/Helper/Page.php(52): Mage_Cms_Helper_Page->_renderPage(Object(Mage_Cms_IndexController), 'no-route')
#8 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Cms/controllers/IndexController.php(75): Mage_Cms_Helper_Page->renderPage(Object(Mage_Cms_IndexController), 'no-route')
#9 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Cms_IndexController->noRouteAction()
#10 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('noRoute')
#11 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#12 /chroot/home/boatstor/boatstore.com/html/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#13 /chroot/home/boatstor/boatstore.com/html/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#14 /chroot/home/boatstor/boatstore.com/html/index.php(87): Mage::run('', 'store')
#15 {main}