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.
You can also test the backup before importing it by dragging and dropping the file to 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