HTTP Status 500 - java.lang.IllegalArgumentException: Invalid index value 'user_email'

type Exception report

message java.lang.IllegalArgumentException: Invalid index value 'user_email'

description The server encountered an internal error that prevented it from fulfilling this request.

exception

java.lang.RuntimeException: java.lang.IllegalArgumentException: Invalid index value 'user_email'
    cn.itcast.utils.WebUtils.request2Bean(WebUtils.java:25)
    cn.itcast.web.controller.RegisterServlet.doGet(RegisterServlet.java:21)
    cn.itcast.web.controller.RegisterServlet.doPost(RegisterServlet.java:57)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:643)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
root cause

java.lang.IllegalArgumentException: Invalid index value 'user_email'
    org.(DefaultResolver.java:100)
    org.(BeanUtilsBean.java:917)
    org.(BeanUtils.java:456)
    cn.itcast.utils.WebUtils.request2Bean(WebUtils.java:21)
    cn.itcast.web.controller.RegisterServlet.doGet(RegisterServlet.java:21)
    cn.itcast.web.controller.RegisterServlet.doPost(RegisterServlet.java:57)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:643)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.39 logs.
我用myeclipse开发用户登录注册界面，提示无效的email值，，，？？这是怎么回事？