Liferay 4.1.3 integration problem

> Hi all,
>  
> I'm trying to run the OPSPortlet in Liferay 4.1.3 running on Tomcat 5.5.17.
> The portlet is found by "Add Content" in Liferay, but when add it i have
> this error:
> //
> .....
>
> Caused by: java.lang.NullPointerException
>         at
> org.orbeon.oxf.pipeline.InitUtils.createProcessor(InitUtils.java:135)
>  
>         at
> org.orbeon.oxf.webapp.ProcessorService.init(ProcessorService.java:76)
>  
>         at
> org.orbeon.oxf.portlet.OPSPortletDelegate.init(OPSPortletDelegate.jav
> a:110)
>         ... 131 more
>  
> .....
>  
>  
> The portlet.xml is
>  
>
> <portlet-app>
>
> <portlet>
>
> <portlet-name>OrbeonFormsPortlet</portlet-name>
>
> <portlet-class>org.orbeon.oxf.portlet.OPSPortlet</portlet-class>
>
> <init-param>
>
> <name>oxf.main-processor.name</name>
>
> <value>{http://www.orbeon.com/oxf/processors}page-flow</value>
>
> </init-param>
>
> <init-param>
>
> <name>oxf.main-processor.input.controller</name>
>
> <value>oxf:/page-flow.xml</value>
>
> </init-param>
>
> <init-param>
>
> <name>oxf.error-processor.name</name>
>
> <value>{http://www.orbeon.com/oxf/processors}pipeline</value>
>
> </init-param>
>
> <init-param>
>
> <name>oxf.error-processor.input.config</name>
>
> <value>oxf:/config/error.xpl</value>
>
> </init-param>
>
> <supports>
>
> <mime-type>text/html</mime-type>
>
> </supports>
>
> <portlet-info>
>
> <title>Sample Orbeon Forms Portlet</title>
>
> <short-title>Sample Orbeon Forms Portlet</short-title>
>
> </portlet-info>
>
> </portlet>
>
> </portlet-app>
>
>  
>
> and  the web.xml
>
> <?xml version="1.0"?>
>
> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application
> 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
>
> <web-app>
>
> <display-name>OrbeonFormsPortlet</display-name>
>
> <context-param>
>
> <param-name>company_id</param-name>
>
> <param-value>liferay.com</param-value>
>
> </context-param>
>
> <listener>
>
> <listener-class>com.liferay.portal.kernel.servlet.PortletContextListener</listener-class>
>
>
> </listener>
>
> <servlet>
>
> <servlet-name>OrbeonFormsPortlet</servlet-name>
>
> <servlet-class>com.liferay.portal.kernel.servlet.PortletServlet</servlet-class>
>
> <init-param>
>
> <param-name>portlet-class</param-name>
>
> <param-value>org.orbeon.oxf.portlet.OPSPortlet</param-value>
>
> </init-param>
>
> <load-on-startup>1</load-on-startup>
>
> </servlet>
>
> <context-param>
>
> <param-name>oxf.resources.factory</param-name>
>
> <param-value>org.orbeon.oxf.resources.PriorityResourceManagerFactory</param-value>
>
>
> </context-param>
>
> <context-param>
>
> <param-name>oxf.resources.webapp.rootdir</param-name>
>
> <param-value>/WEB-INF/resources</param-value>
>
> </context-param>
>
> <context-param>
>
> <param-name>oxf.resources.priority.1</param-name>
>
> <param-value>org.orbeon.oxf.resources.WebAppResourceManagerFactory</param-value>
>
> </context-param>
>
> <context-param>
>
> <param-name>oxf.resources.priority.2</param-name>
>
> <param-value>org.orbeon.oxf.resources.ClassLoaderResourceManagerFactory</param-value>
>
> </context-param>
>
> <context-param>
>
> <param-name>oxf.properties</param-name>
>
> <param-value>oxf:/config/properties.xml</param-value>
>
> </context-param>
>
> <context-param>
>
> <param-name>oxf.main-processor.name</param-name>
>
> <param-value>{http://www.orbeon.com/oxf/processors}page-flow</param-value>
>
> </context-param>
>
> <context-param>
>
> <param-name>oxf.main-processor.input.controller</param-name>
>
> <param-value>oxf:/page-flow.xml</param-value>
>
> </context-param>
>
> <servlet>
>
> <servlet-name>oxf</servlet-name>
>
> <servlet-class>org.orbeon.oxf.servlet.OXFServlet</servlet-class>
>
> <load-on-startup>1</load-on-startup>
>
> </servlet>
>
> <servlet-mapping>
>
> <servlet-name>oxf</servlet-name>
>
> <url-pattern>/</url-pattern>
>
> </servlet-mapping>
>
> <taglib>
>
> <taglib-uri>http://java.sun.com/portlet</taglib-uri>
>
> <taglib-location>/WEB-INF/tld/liferay-portlet.tld</taglib-location>
>
> </taglib>
>
> </web-app>
>
>  
>
> Any idea?
>
>  
>
> Thanks in advance
>