no route matches controller (Rails 3) - ruby-on-rails-3

Question

I'm pretty new to RoR, please help me identify where I am wrong
I get the following error
Routing Error
No route matches {:controller=>"groups"}
Try running rake routes for more information on available routes
when trying to render the following view
<li><%= link_to 'My groups', user_groups_path %></li>
<li><%= link_to 'New group', new_user_group_path %></li>
and here is 'routes.rb' and rake routes output
devise_for :users
resources :users do |user|
resources :groups do |group|
resources :people do |person|
end
end
end
new_user_session GET /users/sign_in(.:format) devise/sessions#new
user_session POST /users/sign_in(.:format) devise/sessions#create
destroy_user_session GET /users/sign_out(.:format) devise/sessions#destroy
user_password POST /users/password(.:format) devise/passwords#create
new_user_password GET /users/password/new(.:format) devise/passwords#new
edit_user_password GET /users/password/edit(.:format) devise/passwords#edit
PUT /users/password(.:format) devise/passwords#update
cancel_user_registration GET /users/cancel(.:format) devise/registrations#cancel
user_registration POST /users(.:format) devise/registrations#create
new_user_registration GET /users/sign_up(.:format) devise/registrations#new
edit_user_registration GET /users/edit(.:format) devise/registrations#edit
PUT /users(.:format) devise/registrations#update
DELETE /users(.:format) devise/registrations#destroy
user_group_people GET /users/:user_id/groups/:group_id/people(.:format) people#index
POST /users/:user_id/groups/:group_id/people(.:format) people#create
new_user_group_person GET /users/:user_id/groups/:group_id/people/new(.:format) people#new
edit_user_group_person GET /users/:user_id/groups/:group_id/people/:id/edit(.:format) people#edit
user_group_person GET /users/:user_id/groups/:group_id/people/:id(.:format) people#show
PUT /users/:user_id/groups/:group_id/people/:id(.:format) people#update
DELETE /users/:user_id/groups/:group_id/people/:id(.:format) people#destroy
groups GET /users/:user_id/groups(.:format) groups#index
POST /users/:user_id/groups(.:format) groups#create
new_user_group GET /users/:user_id/groups/new(.:format) groups#new
edit_user_group GET /users/:user_id/groups/:id/edit(.:format) groups#edit
user_group GET /users/:user_id/groups/:id(.:format) groups#show
PUT /users/:user_id/groups/:id(.:format) groups#update
DELETE /users/:user_id/groups/:id(.:format) groups#destroy
users GET /users(.:format) users#index
POST /users(.:format) users#create
new_user GET /users/new(.:format) users#new
edit_user GET /users/:id/edit(.:format) users#edit
user GET /users/:id(.:format) users#show
PUT /users/:id(.:format) users#update
DELETE /users/:id(.:format) users#destroy
here is 'model.rb'
class User < ActiveRecord::Base
has_many :groups
class Group < ActiveRecord::Base
belongs_to :user
has_many :people
please help me figure out how to fix the problem
many thanks.
UPD
here is solution, it works
I made all changes suggested by #Abibullah and two changes in controllers
view:
<li><%= link_to 'My groups', user_groups_path(current_user) %></li>
<li><%= link_to 'New group', new_user_group_path(current_user) %></li>
routes.rb
resources :users do |user|
resources :groups do |group|
resources :people
end
end
devise_for :users
GroupsController.rb:
def index
#user = current_user
#user.groups = Group.all
was:
def index
#user = current_user
#groups = Group.all
end
UsersController.rb
class Devise::UsersController < DeviseController
def show
end
end

Answer 1

To Create a nested Group Inside User, U need to pass the user_id inside which U are Creating the Group.
For Ex: If I have user1
Then I will use the routes as this:
link_to 'My groups', user_groups_path(user1)
OR
link_to 'My groups', user_groups_path(user1.id)
AND
link_to 'My Group', new_user_group_path(user1)
OR
link_to 'My Group', new_user_group_path(user1.id)
This is to tell that, To which User you are creating the Group.
If U want to access any specific Group, say for ex: grp1
then My url will be
link_to 'My Group', user_group_path(user1, grp1)
THis is a good refrence for routing.
http://guides.rubyonrails.org/routing.html

Answer 2

I think it's obvious. You've got a typo in your
<li><%= link_to 'My groups', user_groups_path %></li>
link. The path should be user_group_path (without the 's') as shown in your rake routes output, instead of the one you've written in your link.