erreurs pour formulaire dynamique

voila l'erreur retenu du fichier log .je pense c la meme
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2009-01-24 12:25:44 StandardWrapperValve[action]: "Servlet.service()" pour la servlet action a généré une exception
java.lang.NullPointerException
	at org.apache.commons.beanutils.PropertyUtils.getSimpleProperty(PropertyUtils.java:1162)
	at org.apache.commons.beanutils.PropertyUtils.getNestedProperty(PropertyUtils.java:772)
	at org.apache.commons.beanutils.PropertyUtils.getProperty(PropertyUtils.java:801)
	at org.apache.struts.util.RequestUtils.lookup(RequestUtils.java:952)
	at org.apache.struts.taglib.html.BaseFieldTag.doStartTag(BaseFieldTag.java:176)
	at org.apache.jsp.WebContent.formulaire_jsp._jspx_meth_html_text_0(formulaire_jsp.java:168)
	at org.apache.jsp.WebContent.formulaire_jsp._jspx_meth_html_form_0(formulaire_jsp.java:118)
	at org.apache.jsp.WebContent.formulaire_jsp._jspService(formulaire_jsp.java:81)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:696)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:474)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:409)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312)
	at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1069)
	at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:455)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:279)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
	at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:507)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
	at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
	at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
	at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
	at java.lang.Thread.run(Unknown Source)