NoMethodError in Spree::Admin::Societies#new undefined method `societies_path'

I am new to spree and ruby on rails. while creating a custom controller in my spree app, I can successfully add link to it in spree admin panel using deface. but when I go to that link, it gives me following error

NoMethodError in Spree::Admin::Societies#new
Showing app/views/spree/admin/societies/_form.html.erb where line #1 raised:
undefined method `societies_path' for #<#<Class:0x007f19cb636898>:0x007f19c5ecacf8>

I don't know from where it is looking for 'societies_path' as I already have updated app/views/spree/admin/societies/new.html.erb to look for 'admin_societies_path', here it is

<%= render 'form' %>
<%= link_to 'Back', admin_societies_path %>

and app/views/spree/admin/societies/_form.html.erb contains

    <%= form_for(@society) do |f| %>
     <% if @society.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@society.errors.count, "error") %> prohibited this society from being saved:</h2>
      <ul>
      <% @society.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>
  <div class="field">
    <%= f.label :address %><br>
    <%= f.text_field :address %>
  </div>
  <div class="field">
    <%= f.label :area %><br>
    <%= f.text_field :area %>
  </div>
  <div class="field">
    <%= f.label :postcode %><br>
    <%= f.number_field :postcode %>
  </div>
  <div class="field">
    <%= f.label :city %><br>
    <%= f.text_field :city %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
    <% end %>

I tried removing link to back also, but it's again giving same error.

config/routes.rb is

mount Spree::Core::Engine, :at => '/'
Spree::Core::Engine.add_routes do
 namespace :admin do
    resource :societies
  end
end

and my app/controllers/spree/admin/societies_controller.rb is

module Spree
 module Admin
 class SocietiesController < Spree::Admin::BaseController
  before_action :set_society, only: [:show, :edit, :update, :destroy]

  def index
    @societies = Society.all
  end

  def show
  end

  def new
    @society = Society.new
  end

  def edit
  end

  def create
    @society = Society.new(society_params)

    respond_to do |format|
      if @society.save
        format.html { redirect_to @society, notice: 'Society was successfully created.' }
        format.json { render :show, status: :created, location: @society }
      else
        format.html { render :new }
        format.json { render json: @society.errors, status: :unprocessable_entity }
      end
    end
  end
  def update
    respond_to do |format|
      if @society.update(society_params)
        format.html { redirect_to @society, notice: 'Society was successfully updated.' }
        format.json { render :show, status: :ok, location: @society }
      else
        format.html { render :edit }
        format.json { render json: @society.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @society.destroy
    respond_to do |format|
      format.html { redirect_to societies_url, notice: 'Society was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    def set_society
      @society = Society.find(params[:id])
    end

    def society_params
      params.require(:society).permit(:name, :url, :building_number, :address, :area, :postcode, :city, :active, :IsDelete)
    end
end
end
end

Any help would be greatly appreciated.

I would suspect that it is this line in _form partial

<%= form_for(@society) do |f| %>

You need to reference the namespace here, so maybe somthing like

<%= form_for([:admin, @society]) do |f| %>

or add your own url

<%= form_for(@society, url: admin_societies_path) do |f| %>