This is a jsp page I've built:

<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="http://richfaces.org/a4j" prefix="a4j" %>





<f:view>
<h:outputText value="Cabeceera" />

<h:panelGroup id="panel">
<a4j:include id="enviar" viewId="/page/c.jsp" />
</h:panelGroup>

<h:outputText value="header" />
<h:form>
<a4j:commandButton action="next" value="fdgdf"></a4j:commandButton>
</h:form>
</f:view>



and the corresponding navegation rules:

<navigation-rule>
<from-view-id>/base.jsp</from-view-id>
<navigation-case>
<from-outcome>next</from-outcome>
<to-view-id>/page/b.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<navigation-rule>
<from-view-id>/page/c.jsp</from-view-id>
<navigation-case>
<from-outcome>next</from-outcome>
<to-view-id>/page/b.jsp</to-view-id>
</navigation-case>
</navigation-rule>
</faces-config>

I also have this other jsp:

<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="https://ajax4jsf.dev.java.net/ajax" prefix="a4j" %>
estoy en c

<h:form>
<a4j:region id="re">
<a4j:commandButton id="b" value="Ir a c" action="next" reRender="panel"></a4j:commandButton>
</a4j:region>
</h:form>



I'm trying to use the a4j:include component to include the second page in the first and it triggers an error, I don't know what it means I wonder si someone can help.
Note that in the first page I can navigate sucessfully via the second button, which does not use the a4j:include component.

The exception trace is this:

org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:322)
com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:130)
org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:108)
org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:216)
com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:87)
com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:117)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:198)
org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:141)
org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:281)


causa raíz

java.lang.NullPointerException
javax.faces.component.UIComponentBase$ChildrenList.remove(UIComponentBase.java:1545)
javax.faces.webapp.UIComponentTag.removeOldChildren(UIComponentTag.java:1197)
javax.faces.webapp.UIComponentTag.doEndTag(UIComponentTag.java:535)
org.ajax4jsf.taglib.html.jsp.IncludeTag.doEndTag(IncludeTag.java:174)
org.apache.jsp.base_jsp._jspx_meth_a4j_include_0(base_jsp.java:200)
org.apache.jsp.base_jsp._jspx_meth_h_panelGroup_0(base_jsp.java:176)
org.apache.jsp.base_jsp._jspx_meth_f_view_0(base_jsp.java:116)
org.apache.jsp.base_jsp._jspService(base_jsp.java:76)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:322)
com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:130)
org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:108)
org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:216)
com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:87)
com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:117)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:198)
org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:141)
org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:281)


I'm using JSF 1.1 with RichFaces 3.1.0