Modal Dialog form in Rails using jQuery

I have a rails form with form_tag for subscriptions. I want to redirect to this page from my home page, as a Modal Dialog Form, if a user is visiting my website for开发者_开发百科 the first time. Here is my rails form code snippet:

<% title "New Profile" %>

<div id="whatwe-do">
<div class="close-button">
    Close
</div>
<%= form_tag '/subscriptions', :id => 'new_subscription' do%>
    <div id="subscription_dialog">
        <div style="margin: 0pt; padding: 0pt; display: inline;">
            <input type="hidden" value="✓" name="utf8">
            <input type="hidden" value="jChrjugvuBT9cq9D5J1eWKq2GehRpuGCN6OkLEVXunw=" name="authenticity_token">
        </div>

        <div class="category-wrapper">
            <div class="category">
                <% for category in @categories %>
                    <strong><%= category.name %></strong>
                    <% for sub_category in category.sub_categories%>
                        <div class="items">
                            <%= check_box_tag "profile[user_interest_ids][]", sub_category.id,
                            @profile.get_user_interests.include?(sub_category.id) %> 
                            <%= sub_category.name %>
                        </div>
                    <% end %>
                <% end %>
            </div>
        </div>
</div>

<div id="email-wrapper"> 
    <%= text_field_tag :email %>
    <%= submit_tag "Send me Deals" %>
</div>
<% end %>

And here's my jQuery script:

$("#subscription_dialog").dialog({modal:true, width:'auto', height:'auto'});

I tried this too:

$("#new_subscription").dialog({modal:true, width:'auto', height:'auto'});

None of these seem to work. Can anyone suggest my how to do a modal dialog form in Rails using jQuery? Thanks.

you made sure that the dom was loaded?

$(function(){
    $("#subscription_dialog").dialog({modal:true, width:'auto', height:'auto'});
})