Redmine

Hello.
I'm pretty sure it's a bug. This is a brand new installation of redmine with some plugins. Everything worked pretty much out of the box. (I'm using 1x elsewhere this is my first 2x Redmine installation). When I go into Workflow > Field Permissions to require some standard fields ( I want users to select category, due date and assigned_to fields ) - the only option I get in a dropdown is 'read-only'. However according to everything I read on forums and issues list it should also have 'required' option. Amy missing something or did I knot do something during install? (I'm pretty sure I followed installation guide to the letter). It's not critical, just really annoying to go into the system and clean up after users - make sure that all bugs have a person and due date assigned and are properly categorized. Some of my users are untrainable :-)

Here are my Redmine details:

Environment:
  Redmine version                          2.3.1.stable 
  Ruby version                             2.0.0 (x86_64-linux)  # Ruby 2.0.0p195 through rbenv on Debian 7
  Rails version                            3.2.13
  Environment                              production
  Database adapter                         PostgreSQL  # 9.2