Cannot convert XML to PDF for report

Hi All,
We have a report where the output of the concurrent program is shown  in XML for a particular transaction type.
The output of the program is in PDF.
The log shows the below message
Beginning post-processing of request 51821287 on node VFILVAPPCLONE at 15-NOV-2012 03:10:33. Post-processing of request 51821287 failed at 15-NOV-2012 03:10:35 with the error message: One or more post-processing actions failed. Consult the OPP service log for details

OPP log has below message :

Template code: XXRAXINV_SEL_IN Template app: XXVFI Language: en Territory: US Output type: PDF
 [11/15/12 3:10:35 AM] [UNEXPECTED] [170573:RT51821287] java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at oracle.apps.xdo.common.xml.XSLT10gR1.invokeProcessXSL(XSLT10gR1.java:673) at oracle.apps.xdo.common.xml.XSLT10gR1.transform(XSLT10gR1.java:421) at oracle.apps.xdo.common.xml.XSLT10gR1.transform(XSLT10gR1.java:240) at oracle.apps.xdo.common.xml.XSLTWrapper.transform(XSLTWrapper.java:182) at oracle.apps.xdo.template.fo.util.FOUtility.generateFO(FOUtility.java:1044) at oracle.apps.xdo.template.fo.util.FOUtility.generateFO(FOUtility.java:997) at oracle.apps.xdo.template.fo.util.FOUtility.generateFO(FOUtility.java:212) at oracle.apps.xdo.template.FOProcessor.createFO(FOProcessor.java:1665) at oracle.apps.xdo.template.FOProcessor.generate(FOProcessor.java:975) at oracle.apps.xdo.oa.schema.server.TemplateHelper.runProcessTemplate(TemplateHelper.java:5926) at oracle.apps.xdo.oa.schema.server.TemplateHelper.processTemplate(TemplateHelper.java:3458) at oracle.apps.xdo.oa.schema.server.TemplateHelper.processTemplate(TemplateHelper.java:3547) at oracle.apps.fnd.cp.opp.XMLPublisherProcessor.process(XMLPublisherProcessor.java:290) at oracle.apps.fnd.cp.opp.OPPRequestThread.run(OPPRequestThread.java:157) Caused by: oracle.xdo.parser.v2.XPathException: Cannot convert to number. at oracle.xdo.parser.v2.XSLStylesheet.flushErrors(XSLStylesheet.java:1534) at oracle.xdo.parser.v2.XSLStylesheet.execute(XSLStylesheet.java:521) at oracle.xdo.parser.v2.XSLStylesheet.execute(XSLStylesheet.java:489) at oracle.xdo.parser.v2.XSLProcessor.processXSL(XSLProcessor.java:271) at oracle.xdo.parser.v2.XSLProcessor.processXSL(XSLProcessor.java:155) at oracle.xdo.parser.v2.XSLProcessor.processXSL(XSLProcessor.java:192) ... 18 more