Error talking to PDF Fill service

I am receiving the following error uploading a PDF document.

[[o:Exception]:"java.lang.Exception: CreateInstance failed: new com.ocdevel.FillpdfService((o:String)[o:String], (o:String)[o:String]). Cause: com.itextpdf.text.exceptions.InvalidPdfException: trailer not found. VM: 1.6.0_20@http://java.sun.com/" at: #-34 com.itextpdf.text.pdf.PdfReader.rebuildXref(PdfReader.java:1520) #-33 com.itextpdf.text.pdf.PdfReader.readPdf(PdfReader.java:511) #-32 com.itextpdf.text.pdf.PdfReader.(PdfReader.java:181) #-31 com.itextpdf.text.pd[...]ort.module(228): _fillpdf_support_get_service('JVBERi0xLjYNJeL...') #7 [internal function]: fillpdf_support_parse_as_fields('JVBERi0xLjYNJeL...') #8 /home/fillpdf-service/public_html/includes/xmlrpcs.inc(211): call_user_func_array('fillpdf_support...', Array) #9 /home/fillpdf-service/public_html/includes/xmlrpcs.inc(70): xmlrpc_server_call(Object(stdClass), 'parse_pdf_field...', Array) #10 /home/fillpdf-service/public_html/xmlrpc.php(13): xmlrpc_server(Array) #11 {main}]

I've tested a one textfield PDF and it works. What could be the issue with my other PDF, is there a way to troubleshoot it?