Answer by Ashlar for Feeds: How to import images using CSV Node Import?

I am not entirely clear on what you are doing, but I had similar problems trying to read a text file in a custom module. Any file used in Drupal must be imported using drupals api using file_save_upload or file_save ( I believe this puts the files in the database for handling by Drupal). These files are saved within the Site directory structure (your download error message suggests yours are not). You may want to check the modules you are using to see if Drupal is saving the file. This process is necessary because browsers do not let outside sites access a users files without their permission.