I'm working with Symfony for a few weeks now and I don't know well the sfPlugin and I'm working on a code that it doesn't written by me but I have to fix it anyway without reinstall itself.
THE PROBLEM:
I added a permission "perm_segreteria" to sf_guard_permission, but it isn't displayed in the form of sf_guard_user.
What I have to do/check to show in sf_guard_user form the new permission?
Maybe you have only to add the permission widget in the generator of your module.
You can try to check inside
plugins/sfGuardPlugin/modules/sfGuardUser/config/generator.yml
if is set sf_guard_user_permission_list under form - display.
If this is your problem, you have to override the plugin module inside your symfony application
(to be sure to not lose your changes when someonelse update the plugin);
basically add a structure of folders inside your app-folder named sfGuardUser/config/generator.yml
then copy the content of the old generator.yml inside yours and make yours changes.