updateRecords File Upload Issue

updateRecords File Upload Issue

I can upload a plain text file via the API but a PDF or Word Document fails with:

9500 Problem occured while processing the request

Module: Candidates
Format: XML
updateRecords

I'm Base64 encoding the contents first and I've been using the example from the documentation:

<FL val="Attach resume"> TVlTUUwgMTkyLjE2OC4xNS40NCAxOTIuMTY4LjE1Ljk1IDE5Mi4xNjguMTUuNzMKRklMRSAxOTIuMTY4LjE1LjQ0IDE5Mi4xNjguMTUuOTUgMTkyLjE2OC4xNS43MwpCQUNLVVAgMTkyLjE2OC4xNS40NCAxOTIuMTY4LjE1Ljk1IDE5Mi4xNjguMTUuNzMK</FL> <FL val="Attach resume_filename">components.txt</FL>

Any help would be appreciated.