Statistics dont work

When I press the statistics menu dont show anything and the error log show the following message:

at org.jivesoftware.openfire.reporting.stats.RrdSqlBackend.read(RrdSqlBackend.java :155)

at org.jrobin.core.RrdBackend.readString(Unknown Source)

at org.jrobin.core.RrdPrimitive.readString(Unknown Source)

at org.jrobin.core.RrdString.get(Unknown Source)

at org.jrobin.core.Header.isJRobinHeader(Unknown Source)

at org.jrobin.core.Header.validateHeader(Unknown Source)

at org.jrobin.core.RrdDb.(Unknown Source)

at org.jrobin.core.RrdDb.(Unknown Source)

at org.jivesoftware.openfire.reporting.stats.StatsEngine$DefaultStatDefinition.fet chData(StatsEngine.java:499)

at org.jivesoftware.openfire.reporting.stats.StatsEngine$DefaultStatDefinition.get Min(StatsEngine.java:541)

at org.jivesoftware.openfire.reporting.stats.DefaultStatsViewer.getMin(DefaultStat sViewer.java:116)

at org.jivesoftware.openfire.reporting.stats.StatsAction.getLowAndHigh(StatsAction .java:175)

at org.jivesoftware.openfire.plugin.monitoring.stats_002ddashboard_jsp._jspService (stats_002ddashboard_jsp.java:167)

at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)

at org.jivesoftware.openfire.container.PluginServlet.handleJSP(PluginServlet.java: 247)

at org.jivesoftware.openfire.container.PluginServlet.service(PluginServlet.java:10 5)

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.ja va:1359)

at org.jivesoftware.admin.PluginFilter.doFilter(PluginFilter.java:78)

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1330)

at org.jivesoftware.admin.AuthCheckFilter.doFilter(AuthCheckFilter.java:164)

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1330)

at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:11 8)

at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1330)

at org.jivesoftware.util.LocaleFilter.doFilter(LocaleFilter.java:74)

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1330)

at org.jivesoftware.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingF ilter.java:50)

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1330)

at org.jivesoftware.admin.PluginFilter.doFilter(PluginFilter.java:78)

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1330)

at org.jivesoftware.admin.AuthCheckFilter.doFilter(AuthCheckFilter.java:164)

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va: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:22 7)

at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:94 1)

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(ContextHandler Collection.java:250)

at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.jav a: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(HttpConne ction.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.jav a: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:724)

Some one can help?

No ideas???