Edit form wrongly being submitted as GET - Rails - ruby-on-rails

Question

I'm trying to edit using a form <%= form_for #agent, :action => 'agents/update', :method => :put do |f| %> but when I click on Save Changes the form is submitted as a GET request instead of a PUT to the update action.
I have resources :agents in my routes.rb file.
In agents_controller.rb the show and update actions are:
def show
#agent = Agent.find(params[:id])
#subscription = #agent.subscription
end
def edit
#agent = Agent.find(params[:id])
#subscription = #agent.subscription
end
def update
#agent = Agent.find(params[:id])
#subscription = #agent.subscription
#agent.update_attributes(:agent)
end
It's pretty depressing when you can't get a standard edit form working, any help appreciated.
EDIT
agents/edit.html.erb
<%= form_for #agent do |f| %>
<ul>
<% for message in #agent.errors.full_messages %>
<li><%= message %></li>
<% end %>
</ul>
<div class="control-group">
<label class="control-label" style="width:200px;margin-right:20px"><strong>First name</strong></label>
<div class="controls">
<%= f.text_field :first_name, :placeholder => 'First name', :class => '', :style => '' %>
</div>
</div>
<div class="control-group">
<label class="control-label" style="width:200px;margin-right:20px"><strong>Last name</strong></label>
<div class="controls">
<%= f.text_field :last_name, :placeholder => 'Last name', :class => '', :style => '' %>
</div>
</div>
<div class="control-group">
<label class="control-label" style="width:200px;margin-right:20px"><strong>Email</strong></label>
<div class="controls">
<%= f.text_field :email, :placeholder => 'Your email', :class => '', :style => '' %>
</div>
</div>
<div class="control-group">
<label class="control-label" style="width:200px;margin-right:20px"><strong>Phone</strong></label>
<div class="controls">
<%= f.text_field :phone, :placeholder => 'Your phone number', :class => '', :style => '' %>
</div>
</div>
<div class="form-actions">
<%= f.submit "Save Changes", :class => 'btn btn-success' %>
<%= link_to 'Cancel', leads_path, :class => 'btn' %>
</div>
<% end %>

Answer 1

You shouldn't need to supply a method nor an action for a simple form like this. A simple
<% form_for #agent do |f| %>
should do you. Have you tried that? Are there any other forms on the page that could be conflicting? If so, try removing those other forms first, then see how that goes.

Answer 2

Fixed it. This post covered the exact same issue: HTML <form> tag causing Rails form to submit a GET instead of POST request
The GET request is being caused by a form tag around the rails form which was there to add the twitter bootstrap styling class "form-horizontal". Removed the extra form tag and it works fine.