JSF这个错误是怎么回事，谢谢了！！！
配置了几天tomcat，终于配置出来了。 写第一个程序还老出错。崩溃啊！！！

HTTP Status 500 - 

--------------------------------------------

type Exception report

message 

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

exception 

javax.servlet.ServletException: /calc.jsp(19,9) '#{culator.msg}' Target Unreachable, identifier 'culator' resolved to null
javax.faces.webapp.FacesServlet.service(FacesServlet.java:256)


root cause 

org.apache.jasper.el.JspPropertyNotFoundException: /calc.jsp(19,9) '#{culator.msg}' Target Unreachable, identifier 'culator' resolved to null
org.apache.jasper.el.JspValueExpression.setValue(JspValueExpression.java:91)
com.sun.faces.application.ApplicationImpl.createComponent(ApplicationImpl.java:213)
javax.faces.webapp.UIComponentELTag.createComponent(UIComponentELTag.java:211)
javax.faces.webapp.UIComponentClassicTagBase.createChild(UIComponentClassicTagBase.java:476)
javax.faces.webapp.UIComponentClassicTagBase.findComponent(UIComponentClassicTagBase.java:660)
javax.faces.webapp.UIComponentClassicTagBase.doStartTag(UIComponentClassicTagBase.java:1111)
com.sun.faces.taglib.html_basic.PanelGridTag.doStartTag(PanelGridTag.java:344)
org.apache.jsp.calc_jsp._jspx_meth_h_005fpanelGrid_005f0(calc_jsp.java:337)
org.apache.jsp.calc_jsp._jspx_meth_h_005fform_005f0(calc_jsp.java:183)
org.apache.jsp.calc_jsp._jspx_meth_f_005fview_005f0(calc_jsp.java:120)
org.apache.jsp.calc_jsp._jspService(calc_jsp.java:83)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:428)
com.sun.faces.application.ViewHandlerImpl.executePageToBuildView(ViewHandlerImpl.java:444)
com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:116)
com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)


note The full stack trace of the root cause is available in the Apache Tomcat/6.0.35 logs.


--------------------------------------------

Apache Tomcat/6.0.35

------解决方案--------------------
javax.servlet.ServletException: /calc.jsp(19,9) '#{culator.msg}' Target Unreachable, identifier 'culator' resolved to null
你的calc.jsp页面有错误
------解决方案--------------------
culator中 有msg变量的get 或者set方法？
我的异常网推荐解决方案：The server encountered an internal error () that prevented it from fulfilling this request.,http://www.aiyiweb.com/java-web/317.html