Merging PDFs through Assembler service returns error

<?xml version="1.0" encoding="UTF-8"?>

<DDX xmlns="http://ns.adobe.com/DDX/1.0/">

    <PDF result="out.pdf">

        <PDF source="map.pdf" baseDocument="true"/>

        <PDF source="directions.pdf"/>

    </PDF>

</DDX>

This is the ddx file I am using as one of the input values .

It fails at this point

assemblerRes = svcAssembler.invoke(ddxBLOB, inputMap, assemblerSpec)

and the error returned is this:

com.adobe.livecycle.assembler.client.OperationException: ALC-ASM-S00-002: Failed to execute the DDX - error messages provided. Caused by: javax.xml.bind.UnmarshalException Caused by: org.xml.sax.SAXParseException: Content is not allowed in trailing section.; nested exception is:
com.adobe.livecycle.assembler.client.OperationException: ALC-ASM-S00-002: Failed to execute the DDX - error messages provided." String

Does this require any special changes in the server side .I have checked for the whitespace in the ddx document and there aren't any.Looks fine.

Any way to resolve this?

Fyi, I am have ES2 and am using it in .net 2.0

Thanks,

Dileep