Sometimes(mostly if installation of template was made on ps version older than 1.7.4) there is a problem with module controllers in backoffice.

To fix it perform following

1. Upgrade ps to latest version

2. Put fix_tabs.php https://github.com/iqit-commerce/tabs-fix/blob/master/fix_tabs.php file in your root prestashop folder and then run script in your browser by www.yourdomain.com/fix_tabs.php

3. Remove file from server