probleme jasperreports pour l affichage des rapports

[yassin_lhabe]

bonjour tout le monde,
j'utilise jasper server version 4.0.0 via les web services dans un application web pour afficher mes rapports , mais j ai rencontre un probleme lorsque je veux afficher ces derniers :

java.lang.NullPointerException

at net.sf.jasperreports.engine.fill.JRTemplatePrintFrame.getTopBorder(JRTemplatePrintFrame.java:136)
at net.sf.jasperreports.engine.export.JRHtmlExporter.appendBorderStyle(JRHtmlExporter.java:1278)
at net.sf.jasperreports.engine.export.JRHtmlExporter.exportFrame(JRHtmlExporter.java:1878)
at net.sf.jasperreports.engine.export.JRHtmlExporter.exportGrid(JRHtmlExporter.java:768)
at net.sf.jasperreports.engine.export.JRHtmlExporter.exportPage(JRHtmlExporter.java:673)
at net.sf.jasperreports.engine.export.JRHtmlExporter.exportReportToWriter(JRHtmlExporter.java:632)
at net.sf.jasperreports.engine.export.JRHtmlExporter.exportReport(JRHtmlExporter.java:371)
at org.apache.jsp.executeReport_jsp._jspService(executeReport_jsp.java:112)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:386)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)

merci d avance pour tout reponce