Import files from wordpress.com to wordpress.org

Hi, I’m trying to import my content from .com to .org, I already installed the app for doing it at .org, but this message comes every time I hit IMPORT AND UPLOAD. Is not reading the file. Any clue of what to do in this case? thanks a lot.

Import WordPress

Sorry, there has been an error.
File is empty. Please upload something more substantial. This error could also be caused by uploads being disabled in your php.ini or by post_max_size being defined as smaller than upload_max_filesize in php.ini.