Multiple pages in portlet

I face the following problem, there are two pages (views) in my portlet, first with rich:tree of components and the second with create/edit form for this components. On the first page I have the following code:

 <s:link value="#{treeitem.name}" view="/view/testSet/testSetCreation.xhtml">
   <a4j:support event="onclick">
       <f:setPropertyActionListener value="#{treeitem}" target="#{testSetParamDto.t}"/>
   </a4j:support>
 </s:link>

When I click on component name occur the following exception:

13:18:12,483 ERROR [SeamPhaseListener] swallowing exception
java.lang.IllegalStateException: Co开发者_开发百科uld not start transaction
        at org.jboss.seam.jsf.SeamPhaseListener.begin(SeamPhaseListener.java:598
)
        at org.jboss.seam.jsf.SeamPhaseListener.begin(SeamPhaseListener.java:583
)
...
13:18:12,790 WARN  [SeamPhaseListener] uncaught exception, passing to exception
handler
java.lang.IllegalStateException: No active conversation context
        at org.jboss.seam.core.Conversation.instance(Conversation.java:122)
        at org.jboss.seam.faces.FacesManager.prepareBackswitch(FacesManager.java
:260)

Can anyone tell me what am I doing wrong? Thank you

---

Whats happening here?

<f:setPropertyActionListener value="#{treeitem}" target="#{testSetParamDto.t}"/>

Show us a example code and the whole exception please.