Delete link doesn't work but button does

I have a problem very similar to this one: rails 3 - link_to to destroy not working

But delete/destroy links do not work; I simply get redirected to the show page of the object. When I make a button for delete, it all works fine. But I'd like to understand why. Does anyone know?

I seems to be related to some .js files I am using/calling.

<!-- This link doesn't work -->
<%= link_to('Delete', post, :confirm => 'Are you sure?', :method => :delete) %>-->

<!-- This button does work -->
<%= button_to "delete", post, :method=>:delete, :class=>:destroy, :confirm => 'Are you sure?' %>

Post Controller

def destroy
  @post = Post.find(params[:id])
  @post.destroy

respond_to do |format|
  format.html { redirect_to(posts_url) }
  format.xml  { head :ok }
end

end

UPDATE After doing some further research it seem that everyone else having a similiar issue has included the following jquery library:

<script type="text/javascript" src="/javascripts/dragdrop.js"><开发者_运维知识库;/script>

But I still don't know what the issue is...

LOG

Started GET "/posts/7" for 127.0.0.1 at Tue Jul 12 08:34:06 -0400 2011
Processing by PostsController#show as HTML
Parameters: {"id"=>"7"}
Post Load (0.2ms)  SELECT "posts".* FROM "posts" WHERE "posts"."id" = 7 LIMIT 1
SQL (0.2ms)  SELECT COUNT(*) FROM "comments" WHERE ("comments".post_id = 7)
Rendered posts/show.html.erb within layouts/application (116.5ms)

HTML generated

<a href="/posts/17" data-confirm="Are you sure?" data-method="delete" rel="nofollow">Delete</a>

UPDATE: I've found that removing <script type="text/javascript" src="/javascripts/jquery-1.5.1.min.js"></script> fixes my problem. But I don't understand why. Is there a known conflict between jquery1.5.1 and rails 3.0.7?

Make sure you include these in your application layout:

<%= javascript_include_tag(:defaults) %>
<%= csrf_meta_tag %>

In my case adding

<%= javascript_include_tag(:defaults) %>

did not work. However explicitly defining java script files did the trick

<%= javascript_include_tag 'prototype' %>
<%= javascript_include_tag 'application' %>

Not sure yet why :defaults tag didn't work...

Rails will automatically load jquery for you if you have jquery-rails gem loaded via your Gemfile (this is the default rails configuration). It is then loaded via:

<%= javascript_include_tag(:defaults) %>

Have a look at app/assets/javascripts/application.js for the code that tells rails to add jquery via assets:

//= require jquery
//= require jquery_ujs

By trying to load another copy of jquery via this line:

<script type="text/javascript" src="/javascripts/jquery-1.5.1.min.js"></script>

You have caused a clash of jquery instances, the effect of which will be that neither will work.