Rails 3 Tinymce css style error: Failed to load source

I have chosen advanced mode in tiny mce. But in my view I see this:

Which is not the advanced theme of tiny mce.

I have looked in the html for the page and found this with firebug:

<link rel="stylesheet" _mce_href="http://local开发者_运维百科host:3000/javascripts/tiny_mce/themes/simple/skins/default/content.css?1303749502" href="http://localhost:3000/javascripts/tiny_mce/themes/simple/skins/default/content.css?1303749502">
Failed to load source for: http://localhost:3000/javascripts/tiny_mce/themes/simple/skins/default/content.css?1303749502

I have followed this guide to install tiny mce: https://github.com/kete/tiny_mce

Why does it failed to load the source? Do I need to add something to my route file?

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I removed my class from the text field