habtm relation, cannot populate join table

Hai friends,
I hav two models related with habtm

class User < ActiveRecord::Base
  has_and_belongs_to_many :station,
                          :join_table => "stations_users",
                          :foreign_key => "user_id",
                          :association_foreign_key => "station_id"

class Station < ActiveRecord::Base
  has_and_belongs_to_many :user
end

When i create a new user its user_id and the station _id is not inserted
into the "stations_users" table.I hav used scaffolding 4 creating these
two models.How can i insert the fields for the join table also when a
user is created?
Can any one help me?

Thanks and regards,
Veena

Hai friends,
I hav two models related with habtm

class User < ActiveRecord::Base
has_and_belongs_to_many :station,
:join_table => "stations_users",
:foreign_key => "user_id",
:association_foreign_key => "station_id"

Shouldn't this be
   has_and_belongs_to_many :stations

The plurality is important. Also with that change the join_table,
foreign_key and association_foreign key options are unnecessary since
those are the defaults.

class Station < ActiveRecord::Base
has_and_belongs_to_many :user

And this should be
    has_and_belongs_to_many :users

end

When i create a new user its user_id and the station _id is not inserted
into the "stations_users" table.I hav used scaffolding 4 creating these
two models.How can i insert the fields for the join table also when a
user is created?
Can any one help me?

Not sure that this is your problem, but I wouldn't be surprised.

Hai Rick,

   I have made the change you hav told. Still the join table is not been
populated.
These are my migration data.Is there any problem with this?
.....................................................
class CreateNewStations < ActiveRecord::Migration
  def self.up
    create_table :stations do |t|
      t.string :name
      t.integer :district_id
      t.string :MDT_id
      t.string :sim_no
      t.decimal :longitude, :precision=>10, :scale=>6
      t.decimal :latitude, :precision=>10, :scale=>6
      t.integer :user_id
      t.timestamps

    end
    create_table :stations_users, :id => false do |t|
      t.integer :user_id
      t.integer :station_id
    end
  end

  def self.down
   drop_table :stations_users rescue nil
    drop_table :stations
  end
end
...........................................................

class CreateUsers < ActiveRecord::Migration
  def self.up
    create_table :users do |t|
      t.string :name
      t.string :username
      t.string :hashed_password
      t.string :salt
      t.string :status
      t.string :phone
      t.string :email
      t.integer :station_id
      t.timestamps
    end
  end

  def self.down
    drop_table :users
  end
end

Thanks and Regards,
Veena

Hai Rick,

I have made the change you hav told. Still the join table is not been
populated.
These are my migration data.Is there any problem with this?
.....................................................
class CreateNewStations < ActiveRecord::Migration
def self.up
create_table :stations do |t|
t.string :name
t.integer :district_id
t.string :MDT_id
t.string :sim_no
t.decimal :longitude, :precision=>10, :scale=>6
t.decimal :latitude, :precision=>10, :scale=>6
t.integer :user_id

I don't think you want this field. This would be there if you had

    class Stations < ActiverRecord::Base
        belongs_to :user
    end

but you indicated that each station could have many users, and each
user could have many stations, thus the habtm relations.