zk 6.0.1 error load applet

[solved] wasn't a zk problem but was due to an updated verision of tomcat Hello, I'm testing a zul page, runnig well on zk 5.0.11, on zk 6.01 I have this error when loading a very simple page "applet.zul" Error is giu 19, 2012 7:16:32 PM org.apache.catalina.core.ApplicationDispatcher invoke Grave: Servlet.service() for servlet zkLoader threw exception java.lang.NullPointerException at org.zkoss.web.servlet.Servlets.getVersion(Servlets.java:449) at org.zkoss.web.servlet.Servlets.getVersion(Servlets.java:446) at org.zkoss.web.servlet.Servlets.browserInfo(Servlets.java:408) at org.zkoss.web.servlet.Servlets.browserInfo(Servlets.java:360) at org.zkoss.web.servlet.Servlets.getBrowser(Servlets.java:323) at org.zkoss.zk.ui.http.ExecutionImpl.(ExecutionImpl.java:102) at org.zkoss.zk.ui.http.TemporaryExecution.(TemporaryExecution.java:41) at org.zkoss.zk.ui.http.WebManager.newDesktop(WebManager.java:475) at org.zkoss.zk.ui.http.WebManager.getDesktop(WebManager.java:461) at org.zkoss.zk.ui.http.DHtmlLayoutServlet.process(DHtmlLayoutServlet.java:186) at org.zkoss.zk.ui.http.DHtmlLayoutServlet.doGet(DHtmlLayoutServlet.java:135) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684) at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:471) at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329) at org.apache.catalina.authenticator.FormAuthenticator.forwardToLoginPage(FormAuthenticator.java:413) at org.apache.catalina.authenticator.FormAuthenticator.authenticate(FormAuthenticator.java:279) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:544) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1812) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) I'm using tomcat 7.0.27 and java jdk 1.7.0_05 Do someone have any idea ? Thank you Giuseppe