Lazy loading problem

[xtia004]

I have an SFSB with name "invoiceListAction" in session scope. An entity manager with extended persistence context type is injected. When within a dataTable, I use following code to call a method of invoiceListAction. The lazy loading works well.

 <s:link styleClass="link_font" action="#{invoiceListAction.exportToPdf}">
 <t:graphicImage url="/media/pdf-icon.gif" />
 </s:link>

The method "exportToPdf" calls anthor method "getSelectedInvoice" that annotated by @DataModelSelection at invoiceListAction to get an invoice instance. The address property of agency is in lazy fetch type.

But if not within a dataTable, I used two ways to access the lazy loaded property, exception raised as "failed to lazily initialize a collection of role".
One way is using exactly the same code as above. And the other way is as below:

<c:set var="add" value="#{invoiceListAction.selectedInvoice.agency.primaryAddress}" scope="page" />

Could anybody help me for this?

[xtia004]

By further probing my code, I found it is actually caused by em.clear at another component. i.e. when I select a row at dataTable, the following code is executed:

InvoiceContacts invoiceContactsAction = (InvoiceContacts) Component.getInstance("invoiceContactsAction",
 ScopeType.SESSION);
invoiceContactsAction.changeInvoice(getSelectedInvoice());

And code at component invoiceContactsAction is below:

@Stateful
@Name("invoiceContactsAction")
@Scope(ScopeType.SESSION)
public class InvoiceContactsAction implements InvoiceContacts {

 @PersistenceContext
 EntityManager em;

 ...

 public void changeInvoice(Invoice selectedInvoice) {
 this.selectedInvoice = selectedInvoice;
 tempList = null;
 invContacts = null;
 em.clear();
 }

 ...
}

So the question turn out to be: Why does clearing the entity manager at a component make the entity bean retrieved by another component detached under this situation?

[gavin.king]

because there is a single persistence context for the whole transaction