FIX: #2664 it should be validates not validate

Thanks @chancancode

app/controllers/admin/groups_controller.rb

@@ -23,12 +23,12 @@ class Admin::GroupsController < Admin::AdminController
   def update
     group = Group.find(params[:id].to_i)
 
+    group.alias_level = params[:group][:alias_level].to_i if params[:group][:alias_level].present?
+
     if group.automatic
       # we can only change the alias level on automatic groups
-      group.alias_level = params[:group][:alias_level]
     else
       group.usernames = params[:group][:usernames]
-      group.alias_level = params[:group][:alias_level]
       group.name = params[:group][:name] if params[:group][:name]
     end
     group.visible = params[:group][:visible] == "true"

app/models/group.rb

@@ -34,7 +34,7 @@ class Group < ActiveRecord::Base
     :everyone => 99
   }
 
-  validate :alias_level, inclusion: { in: ALIAS_LEVELS.values}
+  validates :alias_level, inclusion: { in: ALIAS_LEVELS.values}
 
   def posts_for(guardian, before_post_id=nil)
     user_ids = group_users.map {|gu| gu.user_id}