[Fedora-packaging] mime type not associating with gui application

How do I create my spec file so that I my gui application can be launched by double clicking a filetype it is associated with via mimetype? This is what I've done so far: - I have updated my .desktop file so that it includes MimeType=application/x-supes-saved; - In my spec I have successfully used xdg-mime and xdg-icon-resource so that files with my custom extension (.supes) has my custom icon. But when I double click on one of my files, I am prompted with a modal dialog "There is no application installed for Superman Saved Game files". When I opt to "Select Application" my application is not listed either. (The application's desktop icon is successfully installed and runs under the application menu). Any suggestions? Thank you.