Submit_to_remote fails on rails 2.2.2

submit_to_remote fails on rails 2.2.2 and rails 2.3.2 but fully
working with 2.0.2

please give me an answer as soon as possible. its very urgent

the code is

HTML

<% form_for :todo, @todo, :url => { :action => “update_todo” } do |f|
%>

Todo <%=f.text_field :name%>

Description <%=f.text_area :description,:rows=>3 %>

Due date <%=f.text_field :due_date,:class=>"date-pick dp-applied" %>

Assign to <%=select("todo", "assign_to", @project.project_teams.map {|u| [User.find (u.user_id).full_name,u.user_id]}.uniq)%>

<%= submit_to_remote 'create_btn', 'Update', :url => { :action => 'update_todo',:id=>@project.id,:todo_id=>@todo.id} %>

<%end%>

Controller

def update_todo
@todo = Todo.find(params[:todo_id])
@todo.update_attributes(params[:todo])
@todo.save
end