Openfire can't create one more persistent MultiUserChat room

I have build a XMPP server with openfire ,everything runs ok in the beginning. while something wrong comes after adding some plugins on it,i can only create one multiUserChat ,if one more ,it throws NullPointException,here is the stacktrace:

java.lang.NullPointerException
     
at org.jivesoftware.openfire.muc.spi.MUCPersistenceManager.loadFromDB(MUCPersistenceManager.java:176)
at org.jivesoftware.openfire.muc.spi.MultiUserChatServiceImpl.getChatRoom(MultiUserChatServiceImpl.java:583)
at org.jivesoftware.openfire.admin.muc_002droom_002dedit_002dform_jsp._jspService(muc_002droom_002dedit_002dform_jsp.java:178)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:547)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1359)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:118)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1330)
at org.jivesoftware.util.LocaleFilter.doFilter(LocaleFilter.java:74)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1330)
at org.jivesoftware.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:50)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1330)
at org.jivesoftware.admin.PluginFilter.doFilter(PluginFilter.java:78)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1330)
at org.jivesoftware.admin.AuthCheckFilter.doFilter(AuthCheckFilter.java:164)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1330)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:478)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:520)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:227)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:941)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:409)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:186)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:875)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117)
at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:250)
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:149)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:110)
at org.eclipse.jetty.server.Server.handle(Server.java:349)
at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.java:441)
at org.eclipse.jetty.server.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:919)
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:582)
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:218)
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:51)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:586)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:44)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:598)
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:533)
at java.lang.Thread.run(Thread.java:744)