JasperReports encountered this error :
java.lang.NullPointerException
	at it.irex.spago.presentation.rendering.JasperRenderer.render(JasperRenderer.java:78)
	at it.eng.spago.dispatching.httpchannel.AdapterHTTP.render(AdapterHTTP.java:551)
	at it.eng.spago.dispatching.httpchannel.AdapterHTTP.service(AdapterHTTP.java:449)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:674)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:465)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:400)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:303)
	at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:195)
	at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:159)
	at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
	at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
	at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
	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.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:300)
	at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:383)
	at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:743)
	at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:675)
	at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:866)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
	at java.lang.Thread.run(Unknown Source)