[oXygen-user] using custom parser in saxon 9 transformation scenario

Hi, I'm new to oxygen, but I have written a custom uri resolver which references a custom parser, for saxon 9. The parser reads a binary format file, and returns xml events to saxon. It seems to work well interactively; now I would like to use it in the oxygen xslt debugging environment. I have configured a transformation scenario with the appropriate classes on the class path including both the resolver and the parser and classes upon which they depend. However when I invoke the transformation, I get "Content is not allowed in prolog", which looks to me like the parser isn't getting first crack at the binary data. Does anyone have a suggestion to help with this? Cheers, Peter