You are seeing this message because the file that you are trying to load is not recognised as a WordPress backup. It is not valid or does not have .wpress extension.
Please make sure that the file was created by exporting with the All in One WP Migration plugin.
If you have a file that was provided to you to load a demo or theme, please make sure that it is extracted from the zip file.
You can test .wpress files before importing using our analyser tool at http://traktor.servmask.com. If the file loads to 100% then it is OK to import.
If you have a file that is valid in traktor but will not load, please email our customer service team: support at servmask dot com
It would be great to know the path of backups to be able to check this via the command line or an ftp client.