Content is not allowed in prolog error

[Zulfikar_Soni]

Hi ,

I have a pipeline , through which I am trying to aggregate some xml and 
later transform it through an xsl

like, 
         <map:match pattern="abc">
            <map:act type="request">
                        <map:generate 
src="http://abc.com?STRING={request-param:STRING}""/> 
                </map:act> 
                        <map:serialize type="xml"/>
            </map:match> 
and then i call this repeated in aggregate

<map:match pattern="aggabc">
              <map:aggregate element="abcagg">
                        <map:part 
src="http://localhost:9080/abc?STRING=a"/>
                        <map:part 
src="http://localhost:9080/abc?STRING=b"/>
                        <map:part 
src="http://localhost:9080/abc?STRING=c"/>
                </map:aggregate> 
        <map:transform type="xsltc" src="xyz.xsl"/>
         <map:serialize type="text"/>
       </map:match> 

Sometimes this runs successfully, sometimes it fails. The times when it 
fails is random and this is the what the error says
Could anybody throw some light on this:

Exception: org.xml.sax.SAXParseException: Content is not allowed in 
prolog.

        at 
com.documentum.xerces_2_3_0.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown
 
Source)

        at 
com.documentum.xerces_2_3_0.xerces.util.ErrorHandlerWrapper.fatalError(Unknown 
Source)

        at 
com.documentum.xerces_2_3_0.xerces.impl.XMLErrorReporter.reportError(Unknown 
Source)

        at 
com.documentum.xerces_2_3_0.xerces.impl.XMLErrorReporter.reportError(Unknown 
Source)

        at 
com.documentum.xerces_2_3_0.xerces.impl.XMLScanner.reportFatalError(Unknown 
Source)

        at 
com.documentum.xerces_2_3_0.xerces.impl.XMLDocumentScannerImpl$PrologDispatcher.dispatch(Unknown
 
Source)

        at 
com.documentum.xerces_2_3_0.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown
 
Source)

        at 
com.documentum.xerces_2_3_0.xerces.parsers.DTDConfiguration.parse(Unknown 
Source)

        at com.documentum.xerce

Thanks, 
Zulfikar

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