Link in YUI js not rendered by rails.

Using YAHOO.widget.treeview to generate a table with three levels of
data: module, submodule, and detail. If there is an image associated
with a detail row the javascript generates a link:

    "<td><a href=\"/screenshot/show/" + + "\">Screenshot</


that is appended to the html for the row.

The url is generated correctly and the link appears. When clicked
nothing happens except the word 'Done' appears in the browser status

Am calling the very same url from another page that does not use
javascript and the screenshot page appears as expected.

Here is the controller.

class ScreenshotController < ApplicationController
  def show
      if @detail.screen_path.length > 1
    @imagePath = "#{RAILS_ROOT}" +
      "/private/#{Company.find(@detail.company_id).subdir}/" +
      "#{Project.find(@detail.project_id).subdir}/screenshot/" +
       send_file ( @imagePath, :type => 'image/jpeg', :disposition =>

A sample url: http://localhost:3004/screenshot/show/20854

This code from show.html.erb belonging to the detail model works:
<%= link_to '<b>View</b>', :controller => 'screenshot', :id =>, :action => 'show' %>

Any ideas???