I am trying to convert this document: http://www.redbooks.ibm.com/redpapers/pdfs/redp5213.pdf
to JSON answer units, but it (and many similar others) just won't process through the service. If I try to process it through the demo page at https://document-conversion-demo.mybluemix.net/ it either returns the error 'Missing required parameters: either params.file or params.document_id must be specified' or it simply returns a blank result. If I try it through the REST API via Node.js and watson-developer-cloud, it returns error code 400 along with the message 'The input document failed to be converted because Exception while converting PDF to HTML'. (Why it's trying to convert to HTML I have no clue - I've specified JSON answer units and this code has worked fine with some other documents I've tried).
Is there something unusual about these redpapers that I'm trying to convert, or is the document conversion service having issues?