backingBean doens't receive commandButton action

Question

Im using a rendered commandButton and other button to save input data, But the backing bean doens't receive input from view. I tried all proposition in this post[post]but still doens't work, any help, thanks in advance here is a part of the code:

<ui:define name="content">
   <div class=" marginA">
     <div class="row">
       <ul class="E">

     <p:dataList value="#{userManager.user.diplomas}" var="d">
          <h:panelGrid columns="2">
               <h:panelGrid columns="1" cellpadding="2">
                  <h:outputText  value="#{d.title}"/>
                   <h:outputText value="in #{d.dateDiploma} }"/>
               </h:panelGrid>
         </h:panelGrid>
    </p:dataList>
                     </ul>

   <p:commandButton action="#{userManager.switchEdit(true)}"
                    icon="ui-icon-plus"
                    type="submit"
                    immediate="true"
                    update="add"
                    ajax="true">
    </p:commandButton>

       <h:panelGrid columns="4" cellpadding="5" >
         <h:outputLabel for="diploma" value="Diploma:"/>
                <p:inputText   id="diploma"
                               value="#{userManager.diploma.title}"
                               required="true">
                </p:inputText>
                <p:commandButton value="add"
                         actionListener="#{userManager.addDiploma()}"
                         imediate="true"
                         ajax="true"
                         process="@this"
                         icon="ui-icon-check" />
     </h:panelGrid>

   </div>
 </div>