Please check the file size and format of the file against our instructions. Only certain file types (eg JPG, PNG, PDF, EPUB, ZIP) are accepted by the portal, up to a maximum of 50MB.
Please note that if you have already changed the status of the title to the next phase ie Submitted for Unlatching, then you cannot replace the file. We can do this manually for you.
If this does not help, please get in touch with us using the chat window so that we can investigate.