title: Magento empty blank product page
body: <p>I got some problems with my magento store. The product page view is empty.</p>
  
  <p>I've debugged it and in the exception log I got this message:</p>
  
  <pre><code>2014-02-18T21:45:34+00:00 ERR (3): 
  exception 'Mage_Core_Exception' with message 'Method "addJqueryLibrary" is not defined in "Magentothem_Upsellslider_Model_Layout_Generate_Observer"' in /home/mellimello/public_html/app/Mage.php:595
  Stack trace:
  #0 /home/mellimello/public_html/app/code/core/Mage/Core/Model/App.php(1340): Mage::throwException('Method "addJque...')
  #1 /home/mellimello/public_html/app/code/core/Mage/Core/Model/App.php(1317): Mage_Core_Model_App-&gt;_callObserverMethod(Object(Magentothem_Upsellslider_Model_Layout_Generate_Observer), 'addJqueryLibrar...', Object(Varien_Event_Observer))
  #2 /home/mellimello/public_html/app/Mage.php(448): Mage_Core_Model_App-&gt;dispatchEvent('controller_acti...', Array)
  #3 /home/mellimello/public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(351): Mage::dispatchEvent('controller_acti...', Array)
  #4 /home/mellimello/public_html/app/code/core/Mage/Catalog/Helper/Product/View.php(73): Mage_Core_Controller_Varien_Action-&gt;generateLayoutBlocks()
  #5 /home/mellimello/public_html/app/code/core/Mage/Catalog/Helper/Product/View.php(144): Mage_Catalog_Helper_Product_View-&gt;initProductLayout(Object(Mage_Catalog_Model_Product), Object(Mage_Catalog_ProductController))
  #6 /home/mellimello/public_html/app/code/core/Mage/Catalog/controllers/ProductController.php(132): Mage_Catalog_Helper_Product_View-&gt;prepareAndRender(6, Object(Mage_Catalog_ProductController), Object(Varien_Object))
  #7 /home/mellimello/public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Catalog_ProductController-&gt;viewAction()
  #8 /home/mellimello/public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action-&gt;dispatch('view')
  #9 /home/mellimello/public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard-&gt;match(Object(Mage_Core_Controller_Request_Http))
  #10 /home/mellimello/public_html/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front-&gt;dispatch()
  #11 /home/mellimello/public_html/app/Mage.php(684): Mage_Core_Model_App-&gt;run(Array)
  #12 /home/mellimello/public_html/index.php(87): Mage::run('', 'store')
  #13 {main} 
  </code></pre>