关于JSF的下拉列表 急啊

<h:selectOneMenu id="type" required="true" value="#{jsf1.fj.type}">
      <f:selectItems value="#{jsf1.testTypes}"/>
  </h:selectOneMenu>
testTypes是一个Map对象对应的Java内容：
    public Map getTestTypes() {
        testTypes = new TreeMap();
        testTypes.put(new Integer(1), new String("lyc"));
        testTypes.put(new Integer(2), new String("gxy"));
        return testTypes;
    }
显示的时候没错，但是提交时候就会出错，控制台错误如下：2006-10-9 21:46:58 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet Faces Servlet threw exception
java.lang.IllegalArgumentException
at javax.faces.component.SelectItemsIterator.next(SelectItemsIterator.java:124)
at javax.faces.component.UISelectOne.matchValue(UISelectOne.java:141)
at javax.faces.component.UISelectOne.validateValue(UISelectOne.java:114)
at javax.faces.component.UIInput.validate(UIInput.java:634)
at javax.faces.component.UIInput.executeValidate(UIInput.java:838)
at javax.faces.component.UIInput.processValidators(UIInput.java:412)
at javax.faces.component.UIForm.processValidators(UIForm.java:170)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:904)
at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:342)
at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:78)
at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:90)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:197)
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:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)