generate xsl to fo conversion problem

I give the command
sh /home/vinod/FOP/fop-1.0/fop -xsl rapg_internal.xsl -xml oldxmlformat.xml -pdf myfile.pdf

But I got error as follows :

25 May, 2011 8:56:00 PM org.apache.fop.cli.Main startFOP
SEVERE: Exception
org.apache.fop.apps.FOPException: org.apache.fop.fo.ValidationException: First element must be the fo:root formatting object. Found (Namespace URI: "", Local Name: "head") instead. Please make sure you're producing a valid XSL-FO document.
javax.xml.transform.TransformerException: org.apache.fop.fo.ValidationException: First element must be the fo:root formatting object. Found (Namespace URI: "", Local Name: "head") instead. Please make sure you're producing a valid XSL-FO document.
at org.apache.fop.cli.InputHandler.transformTo(InputHandler.java:302)
at org.apache.fop.cli.InputHandler.renderTo(InputHandler.java:130)
at org.apache.fop.cli.Main.startFOP(Main.java:174)
at org.apache.fop.cli.Main.main(Main.java:205)
Caused by: javax.xml.transform.TransformerException: org.apache.fop.fo.ValidationException: First element must be the fo:root formatting object. Found (Namespace URI: "", Local Name: "head") instead. Please make sure you're producing a valid XSL-FO document.
at org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.java:1323)
at org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(TransformerImpl.java:2411)
at org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.java:1374)
at org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(TransformerImpl.java:2411)
at org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(TransformerImpl.java:2281)
at org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerImpl.java:1367)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:709)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:1284)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:1262)
at org.apache.fop.cli.InputHandler.transformTo(InputHandler.java:299)
... 3 more
Caused by: org.apache.fop.fo.ValidationException: First element must be the fo:root formatting object. Found (Namespace URI: "", Local Name: "head") instead. Please make sure you're producing a valid XSL-FO document.
at org.apache.fop.events.ValidationExceptionFactory.createException(ValidationExceptionFactory.java:38)
at org.apache.fop.events.EventExceptionManager.throwException(EventExceptionManager.java:54)
at org.apache.fop.events.DefaultEventBroadcaster$1.invoke(DefaultEventBroadcaster.java:175)
at $Proxy0.invalidFORoot(Unknown Source)
at org.apache.fop.fo.FOTreeBuilder$MainFOHandler.startElement(FOTreeBuilder.java:261)
at org.apache.fop.fo.FOTreeBuilder.startElement(FOTreeBuilder.java:171)
at org.apache.xml.serializer.ToXMLSAXHandler.closeStartTag(ToXMLSAXHandler.java:204)
at org.apache.xml.serializer.ToSAXHandler.flushPending(ToSAXHandler.java:277)
at org.apache.xml.serializer.ToXMLSAXHandler.startPrefixMapping(ToXMLSAXHandler.java:348)
at org.apache.xml.serializer.ToXMLSAXHandler.startPrefixMapping(ToXMLSAXHandler.java:318)
at org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.java:1315)
... 12 more

Please give me solution.