org.hibernate.LazyInitializationException when migrating webapp to JSF 2.1 & RichFaces 4 - spring

Question

I know this question has been asked a lot, but the strange thing here is that I had no problems when using jsf 1.1 / richfaces 3, along with hibernate 3.7 and spring 2.5.
Now that I migrated my front-end to jsf 2.1 / richfaces 4 (hibernate and spring remained the same) the following exception appears when I try to access a collection marked as "lazy=true" in hibernate mapping config:
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.mu.afs.Afi.cods, no session or session was closed
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358)
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:350)
at org.hibernate.collection.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:97)
at org.hibernate.collection.PersistentBag.size(PersistentBag.java:225)
at javax.faces.model.ListDataModel.isRowAvailable(ListDataModel.java:91)
at javax.faces.model.ListDataModel.setRowIndex(ListDataModel.java:105)
The collection that I try to reach is referenced by a rich:datatable in the same xhtml that the Afi entity;
Here is the part of the xhtml that tries to access the collecion upon an ajax request of a master table:
<rich:extendedDataTable id="tableCods" selectionMode="single"
selection="#{afiBean.codSelected}"
style="width: 100%; height: 100px"
value="#{afiBean.selectedAfi.cods}" var="cod">
...
<rich:column width="50px" style="text-align: right;">
<f:facet name="header"><h:outputText value="Months"/></f:facet>
<h:outputText value="#{cod.months}" />
</rich:column>
<rich:column width="80px" style="text-align: right;">
<f:facet name="header"><h:outputText value="Cap" /> </f:facet>
<h:outputText value="#{cod.cap}">
<f:convertNumber pattern="######,##0.00" locale="es_AR" />
</h:outputText>
</rich:column>
<rich:column width="200px" style="text-align: center;">
<f:facet name="header"><h:outputText value="Class"/></f:facet>
<h:outputText value="#{cod.clazz}" />
</rich:column>
...
Here is my web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
...
<filter>
<filter-name>sessionFilter</filter-name>
<filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>sessionFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
<dispatcher>INCLUDE</dispatcher>
</filter-mapping>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<listener>
<listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
</listener>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/faces/*</url-pattern>
</servlet-mapping>
...
This is part of my application-context.xml:
...
<bean id="txManager"
class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<bean id="txProxyTemplate" abstract="true"
class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
<property name="transactionManager" ref="txManager" />
<property name="transactionAttributes">
<props>
<prop key="save*">PROPAGATION_REQUIRED</prop>
<prop key="store*">PROPAGATION_REQUIRED</prop>
<prop key="get*">PROPAGATION_REQUIRED</prop>
<prop key="read*">PROPAGATION_REQUIRED</prop>
<prop key="load*">PROPAGATION_REQUIRED</prop>
<prop key="*">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>
...
The service that is accessing the Afi entity is defined as follow:
<bean id="afiService" parent="txProxyTemplate">
<property name="proxyInterfaces" value="com.mu.afs.services.AfiService" />
<property name="target">
<bean class="com.mu.afs.services.impl.AfiServiceImpl">
<property name="afiDao" ref="afiDao" />
</bean>
</property>
</bean>
<bean id="afiliadosDao"
class="com.mu.afs.dao.impl.HibernateAfiDaoImpl"
parent="hibernateDaoSupport">
</bean>
I would really appreciate if someone can throw some light on this issue. I dont know whether is related to a migration issue or if there is a problem with this configuration and was somehow "masked" with a previous version of jsf and richfaces.
I tried to put here any relevant information that I thought it would help without boring and overwhelm the reader, but let me know if something is missing here.
Thanks in advance.