rails require_tree and javascript is not working -

my javascripts not working when have = require_tree . inside application.js, if delete js.erb view some_view.js.erb not working.

my application.js file:

/*  = require jquery  = require jquery_ujs  = require jquery-1.7.1.min  = require jquery.validate.min  = require jquery-ui-1.8.23.custom.min  = require jquery.cookie  = require_self  = require_tree .  */ 

any ideas why happening?

the correct manifest file format application.js file looks this:

 //= require_self  //= require jquery  //= require jquery_ujs  //= require jquery.validate.min  //= require jquery-ui-1.8.23.custom.min  //= require jquery.cookie  //= require_tree .