One to Many help

I'm new to Ruby on Rails. I have two tables defined as
Table 1 - Leagues
id primary key - autonum
txtLeagueName

Table 2 - Divisions
id primary key - autonum
league_id
txtDivisionName

I can add a League fine but when I try and add a division I get the
error:
"Couldn't find League without an ID"

I've defined the League table with 'has_many :divisions'
I've defined the Division table with 'belongs_to :league'

Here's a snippet from my divison new.rhtml
<form action="/division/new" method="post">
   <input id="league_id" name="division[league_id]" value="<%=
@league.id %>"/>
  <p>
    <b>Division Name</b><br/>
    <input id="divisionName" name="division[divisionName]" size="30"
type="text" value=""/>
  </p>

You can see I have included league_id as an input field and have passed
the value
as a parameter in the url.(which is working fine, it shows up in the
input field).
When I click on the save button, that's when I get the error above.
I'm not sure
what it's trying to tell me let alone what to do to fix it.

Is your league_id defined as a foreign key?

It seems like it's complaining about not finding the league - are you
trying to find the league in your new method of your controller? I
would assume in the new method you would have something like

@league=League.find(params[:league_id])

What file is the error referring to, the form or the controller?

I do have league_id setup as a foreign key.

It's complaining about my division controller. I do have what you
mention regarding the league parm. Here is a copy of the controller.

class DivisionController < ActionController::Base
    layout "division-layout"
    scaffold :division

  before_filter :initLeague

  def index
    list
    render_action 'list'
  end

  def new
    @division = @league.divisions.new
  end

  def list
    @divisions = @league.divisions.find_all
  end

  def show
    @division = @league.divisions.find(params[:id])
  end

  private
  def initLeague
    @league = League.find(params[:league_id])
    @league_name = @league.txtLeagueName
  end
end