ok i solved the error i posted above Now i am havimng the same exact error as the OP and rafaelco. though i tried different forms of event lsiteners and still the same error. 
I tried in hiberante.cfg.xml: 
Code:
 <event type="post-insert">
       <listener
       class="org.hibernate.envers.event.AuditEventListener" />
       </event>
        <event type="post-update">
       <listener
       class="org.hibernate.envers.event.AuditEventListener" />
       </event>
       
       <event type="post-delete">
       <listener
       class="org.hibernate.envers.event.AuditEventListener" />
       </event> -->
       
       <!-- needed to update the Eclipse Hibernate 3.0 dtd in order to recognise these collection events
       <event type="pre-collection-update">
       <listener
       class="org.hibernate.envers.event.AuditEventListener" />
       </event>
       
       <event type="post-collection-recreate">
       <listener
       class="org.hibernate.envers.event.AuditEventListener" />
       </event>
       
       <event type="pre-collection-remove">
       <listener
       class="org.hibernate.envers.event.AuditEventListener" />
       </event>
I tried in hibnernate.cfg.xml after removing the above ones:
Code:
         <listener class="org.hibernate.envers.event.AuditEventListener" type="post-insert"/>
          <listener class="org.hibernate.envers.event.AuditEventListener" type="post-update"/>
          <listener class="org.hibernate.envers.event.AuditEventListener" type="post-delete"/>
            <listener class="org.hibernate.envers.event.AuditEventListener" type="pre-collection-update"/>
          <listener class="org.hibernate.envers.event.AuditEventListener" type="pre-collection-remove"/>
          <listener class="org.hibernate.envers.event.AuditEventListener" type="post-collection-recreate"/>
And also tried in sprin-config.xml becuase my sessionfactory is made in spring-config.xml:
Code:
 <bean name="session-factory"
          class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"
          p:configLocation="classpath:hibernate.cfg.xml">
           <property name="eventListeners">
            <map>
                <entry key="post-insert" value-ref="enversEventListener"/>
                <entry key="post-update" value-ref="enversEventListener"/>
                <entry key="post-delete" value-ref="enversEventListener"/>
                <entry key="post-collection-recreate" value-ref="enversEventListener"/>
                <entry key="pre-collection-remove" value-ref="enversEventListener"/>
                <entry key="pre-collection-update" value-ref="enversEventListener"/>
            </map>
        </property>
      <!--  <property name="entityInterceptor">
          <bean class="com.illuminatics.losssharing.interceptor.AuditTrailInterceptor"/>
        </property>-->
        
   </bean>
   <bean id="enversEventListener" class="org.hibernate.envers.event.AuditEventListener" />
i am still stuck that my envers does not fill the _aud tables and they remain empty. The original update goes through fine. My application is working fine but the history is not created in revinfo table Nor the _aud table.
I will appreciate if some one has gone through this issue and was able to solve this 
Thanks in advance.
Syed