Creating joins

Im trying to add new records to my joins table. but when ever i click my link to do so i get this error

uninitialized constant Channel::UsersChannel

here is the code

<%= link_to "Subscribe to Channel", subscribe_path(channel, current_user) %>

def subscribe
   @channel = Channel.find(params[:channel_id])
   @user = current_user
   @channel.users << @user
   @channel.save
   flash[:notice] = 'You have subscribed to' + @channel.name
   redirect_to @channel
  end

class User < ActiveRecord::Base
  
  acts_as_authentic
  
  ROLES = %w[admin  moderator subscriber]
  
  #join between users and messages
  has_many :user_messages
  has_many :messages, :through => :user_messages
  #join between users and channels
  has_many :user_channels
  has_many :channels , :through => :users_channels
  #join between mods and channels
  has_many :channel_mods
  has_many :manages, :class_name =>"channel", :through =>:channel_mods
  named_scope :with_role, lambda { |role| {:conditions => "roles_mask & #{2**ROLES.index(role.to_s)} > 0 "} }
  def roles  
    ROLES.reject { |r| ((roles_mask || 0) & 2**ROLES.index(r)).zero? }  
  end
   
  def roles=(roles)  
    self.roles_mask = (roles & ROLES).map { |r| 2**ROLES.index(r) }.sum  
  end
  
  def role_symbols
    role.map do |role|
      role.name.underscore.to_sym
    end
  end
  
  
  
 
  
end

class UsersChannels < ActiveRecord::Base
 belongs_to :user
 belongs_to :channel
end

class Channel < ActiveRecord::Base
 # acts_as_taggable
 # acts_as_taggable_on :tags
  has_many :messages
  has_many :channel_mods
  has_many :moderators , :class_name =>"User", :through => :channel_mods
  has_many :users_channels
  has_many :users, :through => :users_channels

end