Nope, I traced the error. Heh, it was a misspelled start tag :). I wrote xDocument instead of xDocumentClass. Not really a descriptive error message, huh?
After I fixed this one, and did a few mods on the file, i get an even better one :). "Info path encountered an error." without any options for advanced view. It's really strange. I'll have to rerun through the whole file generation procedure to double check what I've done wrong. It's hard though, being there is very little helpful documentation.