Link_to wrong path

HI guys, I’m starting with RoR and I figured I’d jump on the facebook
bandwagon and make a little application… my problem is when using
link_to inside my application I get wrong paths… Let’s say my
application url is Facebook and my application is
hosted at http://someserver.com/main/ (main being my controller). The
problem is that when I use scaffold my links have the wrong path. For
example, <%= link_to ‘Edit’, :action => ‘edit’, :id => torrent %> give
me a link to http://apps.facebook.com/main/edit/1 and not to
http://apps.facebook.com/app/main/edit/1. how can I change this?