只需尝试以下示例即可直接放置观察者类和语法，并且在</smashingmagazine_logproductupdate >之类的唯一标记中有空格，应该为</smashingmagazine_logproductupdate> >

just try with below example to put observer class directly and syntax as well as you have space in unique tag like </smashingmagazine_logproductupdate > this should be </smashingmagazine_logproductupdate>

<events> 
     <checkout_submit_all_after>
          <observers>
            <smashingmagazine_logproductupdate>
                 <class>SmashingMagazine_LogProductUpdate_Model_Observer</class>
                 <method>logUpdate</method>
            </smashingmagazine_logproductupdate>
          </observers>
     </checkout_submit_all_after>
</events>      

希望这一定会帮助您解决问题.

hope this will sure help you to solve your issue.