Form object suddenly can't read my routes?

I'm building a large application where I do everything exactly the
same across most controllers and views. All of them have worked so far
but now, I'm geting the strangest behaviour out of one. I am calling
the same _form.html.erb that fails on either the new or edit action.
I am certain my routes are built correctly but I seem to receive a
message when I'm invoking the form object that it can't find the
route?

NoMethodError in Evidence/etxcodes#edit

Showing evidence/etxcodes/edit.html.erb where line #5 raised:

undefined method `etxcode_path' for #<ActionView::Base:0x554bc6c>

Extracted source (around line #5):

2:
3: <%= error_messages_for :etxcode %>
4:
5: <% form_for(@etxcode) do |form| %>
6: <%= form.error_messages %>
7:
8:

Parameters:

{"account_id"=>"2",
"id"=>"1"}

My edit method is pretty standard and is exactly like all the others

  def edit
    @title = "Edit Transaction Code for: #{@account.name}"
    if current_user.evid_auth > MAX_CONTROL
      @etxcode = @account.etxcodes.find(params[:id])
    else
      flash[:notice] = "You are not authorized to perform this task"
      redirect_back_or_default account_etxcodes_path(@account)
      return false
    end
  end

Actually the functional route that the form object should be using is
edit_account_etxcode_path(@account, @etxcode).
Could anyone recommend how they'd this curious problem?
Thank you,
Kathleen

P.S. All these other routes work correctly;
  map.resources :accounts, :controller => 'admin/accounts' do |
account>
    account.resources :agencies, :name_prefix =>
"account_", :controller => 'evidence/agencies'
    account.resources :incidents, :name_prefix =>
"account_", :controller => 'evidence/incidents'
    account.resources :ecategories, :name_prefix =>
"account_", :controller => 'evidence/ecategories'
    account.resources :etxcodes, :name_prefix =>
"account_", :controller => 'evidence/etxcodes'
    account.resources :ecases, :name_prefix =>
"account_", :controller => 'evidence/ecases'