the page that is returned states that the file was not uploaded correctly. It states that the file my be in the wrong format or that there was a problem with the upload. It's not in the wrong format, i've tried it manually, it's fine.

is there an obvious error with the code? the docs don't really talk about file uploads. i assume it can be done but the docs aren't particularly specific toher than the sentence:

"If the field is of type file (file upload field), the value is always cleared to prevent remote sites from downloading your local files. To upload a file, specify its file name explicitly."