java.lang.IllegalArgumentException: the region is illegal 1[0,-1,0,-1]
	at org.zkoss.zss.model.CellRegion.checkLegal(CellRegion.java:79)
	at org.zkoss.zss.model.CellRegion.<init>(CellRegion.java:91)
	at org.zkoss.zss.model.SheetRegion.<init>(SheetRegion.java:42)
	at org.zkoss.zss.range.impl.RefNotifyContentChangeHelper.handleAreaRef(RefNotifyContentChangeHelper.java:133)
	at org.zkoss.zss.range.impl.RefNotifyContentChangeHelper.notifyContentChange(RefNotifyContentChangeHelper.java:68)
	at org.zkoss.zss.range.impl.RangeImpl.handleRefNotifyContentChange(RangeImpl.java:272)
	at org.zkoss.zss.range.impl.RangeImpl.access$4(RangeImpl.java:270)
	at org.zkoss.zss.range.impl.RangeImpl$ModelUpdateWrapper.doNotify(RangeImpl.java:1745)
	at org.zkoss.zss.range.impl.RangeImpl$ModelManipulationTask.invoke(RangeImpl.java:1694)
	at org.zkoss.zss.model.util.ReadWriteTask.doInWriteLock(ReadWriteTask.java:43)
	at org.zkoss.zss.range.impl.RangeImpl.setHidden(RangeImpl.java:1053)
	at org.zkoss.zss.api.impl.RangeImpl.setHidden(RangeImpl.java:580)
	at org.zkoss.zss.api.CellOperationUtil.hide(CellOperationUtil.java:958)
	at org.zkoss.zss.ui.impl.undo.HideHeaderAction.doAction(HideHeaderAction.java:61)
	at org.zkoss.zssex.ui.impl.UndoableActionManagerImpl.doAction(UndoableActionManagerImpl.java:50)
	at org.zkoss.zss.ui.impl.ua.HideHeaderHandler.processAction(HideHeaderHandler.java:70)
	at org.zkoss.zss.ui.impl.ua.AbstractHandler.process(AbstractHandler.java:60)
	at org.zkoss.zss.ui.impl.DefaultUserActionManagerCtrl.dispatchAuxAction(DefaultUserActionManagerCtrl.java:311)
	at org.zkoss.zss.ui.impl.DefaultUserActionManagerCtrl.onEvent(DefaultUserActionManagerCtrl.java:446)
	at org.zkoss.zssex.ui.impl.UserActionManagerCtrlImpl.onEvent(UserActionManagerCtrlImpl.java:310)
	at org.zkoss.zss.ui.Spreadsheet$4.onEvent(Spreadsheet.java:428)
	at org.zkoss.zk.ui.AbstractComponent.onEvent(AbstractComponent.java:2752)
	at org.zkoss.zk.ui.AbstractComponent.service(AbstractComponent.java:2723)
	at org.zkoss.zk.ui.AbstractComponent.service(AbstractComponent.java:2664)
	at org.zkoss.zk.ui.impl.EventProcessor.process(EventProcessor.java:136)
	at org.zkoss.zk.ui.impl.UiEngineImpl.processEvent(UiEngineImpl.java:1765)
	at org.zkoss.zk.ui.impl.UiEngineImpl.process(UiEngineImpl.java:1550)
	at org.zkoss.zk.ui.impl.UiEngineImpl.execUpdate(UiEngineImpl.java:1260)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.process(DHtmlUpdateServlet.java:611)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.doGet(DHtmlUpdateServlet.java:485)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.doPost(DHtmlUpdateServlet.java:494)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:401)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.Server.handle(Server.java:326)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
	at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:945)
	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756)
	at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
	at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
	at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)