I want to add an icon to a button in ruby on rails. Currently I've tried the following: 

```
<%= button_to raw("<i class=\"icon-arrow-up\"></i>"),
{:controller => 'events', :action => "upvoteEvent", :method => "put",
:id => @event.id, :uid => current_user.id},
{:class => "btn btn-success"}%>

```

which produces the following html: 

```
<form action="/events/upvoteEvent?id=17&amp;method=put&amp;uid=7" class="button_to" method="post"><div><input class="btn btn-success" type="submit" value="<i class="icon-arrow-up"></i>" /><input name="authenticity_token" type="hidden" value="FsVUPiYl0cK666pn8hqo6AU9/HK0CweZ/nsXqwOWZzU=" /></div></form>

```

I've followed the solution posted here: <https://stackoverflow.com/a/10468935/1385324>, but it won't work for me. I have also tested that the Bootstrap CSS is working, by simply inserting an icon anywhere else on the site. 

Thanks for any help!