Convert Entity question

[richardcc.ralbaa.dragosolutions.com]

I'm trying to use convertEntity, this is my page code:

<h:selectOneMenu immediate="true"

     value="${areaList.actionBrowserDefinition}"

     valueChangeListener="#{areaList.selectActionBrowserDefinition}">

     <s:selectItems value="${areaList.actionBrowserDefinitions}"

          var="item" label="#{item.descripcion}" 

          noSelectionLabel="Please Select..."/>

     <a4j:support event="onchange" reRender="op_mdColumnBRW"     ajaxSingle="true" />

     <s:convertEntity/>

</h:selectOneMenu>     

If you select a value with de select I always get call over

"${areaList.actionBrowserDefinition}"

but, if you select  over Please Select..., my EJB is recreated, i get log from @PostConstruct and @Create.

Why?

Thank's