Bootstrap danger class not working for a table row

I have the following table in my Rails app: <table class='table table-bordered table-hover table-striped'> <thead> <tr> <th>ID</th> <th>Status</th> </tr> </thead> <tbody> <tr class='danger'> <td><%= order.id %></td> <td><%= order.status.name %></td> </tr> </tbody> </table> And the row with class 'danger' doesn't change the color. However, if I use the class 'success' it changes correctly. I am using the twitter-bootstrap-rails gem.