Error transforming PDF to PDF/A on LiveCycle PDF Generator ES 8.01

Using the lifecycle remoting we are trying to transform a PDF to PDF/A. Sometime it works and sometimes obviously it doesn't. However, in this case it reports that it can not transform the document as it is protected by a password which is untrue. The original document is not protected by a password. The error is as shown below. Does anyone have any ideas as to why we are seeing this and how to resolve it ?

A+

Caused by: ALC-PDG-11032-000: com.adobe.livecycle.generatepdf.client.ConversionException: ALC-PDG-011-032-Impossible de traiter XXXXXXXXXXX.pdf. Le PDF est protégé par un mot de passe.
at com.adobe.pdfg.Native2PdfCaller.callNativeBMC(Native2PdfCaller.java:4 98)
at com.adobe.pdfg.Native2PdfCaller.createPDF(Native2PdfCaller.java:263)
at com.adobe.pdfg.GeneratePDFImpl.createPDF(GeneratePDFImpl.java:257)
at sun.reflect.GeneratedMethodAccessor2416.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.adobe.idp.dsc.component.impl.DefaultPOJOInvokerImpl.invoke(Defaul tPOJOInvokerImpl.java:181)