关于Liferay的问题在哪里问呀

如题,
我现在用Liferay 写了个关于Struts的例子，老是出错。就是，当登陆后，一点 添加内容后，就报错了。

java.lang.NullPointerException
        at com.liferay.portlet.PortletConfigImpl.getResourceBundle(PortletConfig
Impl.java:147)
        at com.liferay.portal.util.PortalUtil.getPortletTitle(PortalUtil.java:61
8)
        at com.liferay.portal.util.comparator.PortletTitleComparator.compare(Por
tletTitleComparator.java:57)
        at java.util.Arrays.mergeSort(Arrays.java:1278)
        at java.util.Arrays.mergeSort(Arrays.java:1289)
        at java.util.Arrays.sort(Arrays.java:1219)
        at java.util.Collections.sort(Collections.java:155)
        at org.apache.jsp.html.portlet.layout_005fconfiguration.view_005fcategor
y_jsp._jspService(view_005fcategory_jsp.java:422)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:332)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:3
14)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDisp
atcher.java:672)
        at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationD
ispatcher.java:574)
        at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDis
patcher.java:499)
        at com.liferay.taglib.util.IncludeTag.doEndTag(IncludeTag.java:63)
        at org.apache.jsp.html.portlet.layout_005fconfiguration.view_jsp._jspx_m
eth_liferay$1util_include_0(view_jsp.java:535)
        at org.apache.jsp.html.portlet.layout_005fconfiguration.view_jsp._jspSer
vice(view_jsp.java:432)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:332)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:3
14)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDisp
atcher.java:672)
        at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationD
ispatcher.java:574)
        at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDis
patcher.java:499)
        at com.liferay.taglib.util.IncludeTag.doEndTag(IncludeTag.java:63)
        at org.apache.jsp.html.common.themes.portlet_jsp._jspService(portlet_jsp
.java:2571)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:332)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:3
14)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDisp
atcher.java:672)
        at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationD
ispatcher.java:574)
        at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDis
patcher.java:499)
        at com.liferay.portlet.PortletRequestDispatcherImpl.include(PortletReque
stDispatcherImpl.java:237)
        at com.liferay.portal.struts.PortletRequestProcessor.doInclude(PortletRe
questProcessor.java:439)
        at com.liferay.portal.struts.PortletRequestProcessor.doForward(PortletRe
questProcessor.java:414)



然后就是这么一大堆。我就是按着例子一步一步的写的。就是不行。连找错我都不知从何下手。
哪位指点一下。

languages-ext.properties添加title