On Fedora15, following this wiki, I added a user to wheel group, which is already in the sudoer config file.
but still I get not-a-sudoer error prompt. Should I specifically name every member of a group in sudoer file to be able to sudo with that user?
wheelgroup in sudo config file and if it is not commented. Also after modification of groups you need to logout and log in again... – pbm Dec 1 '12 at 20:42