title: UI Layout Initialization Error-The center-pane element does not exist
body: <p>I am using a Layout structure that has centerLayout, westLayout,northLayout </p>
  
  <p>When i run the file, i take this following error:
  "/UI Layout Initialization Error. 
  The center-pane element does not exist. 
  The-center pane is a required element."</p>
  
  <p>my template is :</p>
  
  <p></p>
  
  <pre><code>        &lt;p:layoutUnit position="north" size="100" collapsible="true"&gt;
              &lt;header&gt;
                  &lt;div class="logo1"&gt;
                      &lt;img src="#{facesContext.externalContext.requestContextPath}/resources/images/logo1.png" alt="Gestion d'accès et de habilitations" /&gt;
                  &lt;/div&gt;
                  &lt;ul&gt;
                      &lt;li&gt;&lt;h:link outcome="/profile" value="Profile"/&gt;&lt;/li&gt;
                      &lt;li&gt;&lt;a href="#"&gt;Se déconnecté&lt;/a&gt;&lt;/li&gt;
                  &lt;/ul&gt;
                  &lt;div class="logo2"&gt;
                      &lt;img src="#{facesContext.externalContext.requestContextPath}/resources/images/logo2.png" alt="Altijari Bank" /&gt;
                  &lt;/div&gt;
              &lt;/header&gt;
          &lt;/p:layoutUnit&gt;
  
          &lt;p:layoutUnit position="west" size="210" header="Menus" collapsible="true"&gt;
              &lt;h:form id="frmMenu1"&gt;
                  &lt;p:accordionPanel multiple="true" id="acc" activeIndex="0"&gt;
                      &lt;p:tab title="Gestion des agences"&gt;
                          &lt;p:menu style="width:100%" id="m1"&gt;
                              &lt;p:menuitem value="Consulter" action="#{agenceController.prepareList()}"/&gt;
                              &lt;p:menuitem value="Ajouter" action="#{agenceController.prepareCreate()}" /&gt;                                                          
                          &lt;/p:menu&gt;
                      &lt;/p:tab&gt;
                      &lt;p:tab title="Gestion des utilisateurs"&gt;
                          &lt;p:menu style="width:100%"  id="m2"&gt;
                              &lt;p:menuitem value="Consulter" action="#{utilisateurController.prepareList()}"/&gt;
                              &lt;p:menuitem value="Ajouter" action="#{utilisateurController.prepareCreate()}" /&gt;                                
                          &lt;/p:menu&gt;
                      &lt;/p:tab&gt;
                      &lt;p:tab title="Gestion des fonctions"&gt;
                          &lt;p:menu style="width:100%"  id="m3"&gt;
                              &lt;p:menuitem value="Consulter" action="#{fonctionController.prepareList()}"/&gt;
                              &lt;p:menuitem value="Ajouter" action="#{fonctionController.prepareCreate()}" /&gt;                             
                          &lt;/p:menu&gt;
                      &lt;/p:tab&gt; 
                      &lt;p:tab title="Gestion des applications"&gt;
                          &lt;p:menu style="width: 100%" id="m4"&gt;
                              &lt;p:menuitem value="Consulter" action="#{applicationController.prepareList()}" /&gt;
                              &lt;p:menuitem value="Ajouter" action="#{applicationController.prepareCreate()}"/&gt;
                          &lt;/p:menu&gt;
                      &lt;/p:tab&gt;
                      &lt;p:tab title="Gestion des fiches " &gt;
                          &lt;p:menu style="width: 100%" id="m5"&gt;
                              &lt;p:menuitem value="Consulter" action="#{ficheController.prepareList()}"/&gt;
                              &lt;p:menuitem value="Ajouter" action="#{ficheController.prepareCreate()}" /&gt;
                          &lt;/p:menu&gt;
                      &lt;/p:tab&gt; 
                      &lt;p:tab title="Administration" &gt;
                          &lt;p:menu style="width: 100%" id="m6"&gt;
                              &lt;p:menuitem value="Consulter" action="#{groupeController.prepareList()}"  /&gt;
                              &lt;p:menuitem value="Ajouter" action="#{groupeController.prepareCreate()}" /&gt;
                          &lt;/p:menu&gt;
                      &lt;/p:tab&gt;
                      &lt;p:tab title="Traçabilité" &gt;
                          &lt;p:menu style="width: 100%" id="m7"&gt;
                              &lt;p:menuitem value="Consulter" action="#{traceController.prepareList()}" /&gt;
                              &lt;p:menuitem value="Ajouter" action="#{traceController.prepareCreate()}" /&gt;
                          &lt;/p:menu&gt;
                      &lt;/p:tab&gt;
  
                  &lt;/p:accordionPanel&gt;
              &lt;/h:form&gt;
  
          &lt;/p:layoutUnit&gt;
  </code></pre>
  
  <p>I use primefaces 3.2, jsf 2.1, glassfish 3.1.2.1 
  Please help me.</p>