webwork 开发JSP问题

请问一下这是什么意思呀？
Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause java.lang.NullPointerException
com.opensymphony.webwork.views.jsp.ui.FormTag.evaluateExtraParams(FormTag.java:122)
com.opensymphony.webwork.views.jsp.ui.AbstractUITag.evaluateParams(AbstractUITag.java:408)
com.opensymphony.webwork.views.jsp.ui.AbstractUITag.doEndTag(AbstractUITag.java:204)
org.apache.jsp.registerSupport_jsp._jspx_meth_ww_form_0(org.apache.jsp.registerSupport_jsp:134)
org.apache.jsp.registerSupport_jsp._jspService(org.apache.jsp.registerSupport_jsp:70)
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:322)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available 我的JSP页面是：
<%@ taglib uri="webwork" prefix="ww" %>
<html>
<head><title>Register Example</title></head>
<body>
<table border=0 width=97%>
<tr><td align="left">
<ww:form name="'test'" action="'/example/registerSupport.action'" method="'POST'">
            <ww:textfield label="'Name'" name="'user.name'" required="true"/>
            <ww:textfield label="'Password'" name="'user.password'" required="true"/>
            <ww:textfield label="'VerifyPassword'" name="'verifyPassword'" required="true"/>
            <ww:textfield label="'Email'" name="'user.email'" required="true"/>
            <ww:textfield label="'Age'" name="'user.age'" required="true"/>
            <ww:submit value="'Submit'"/>
         </ww:form>
</td></tr>
</table>
</body>
</html>