Rename hello_world rails app

Hi,

I just ftp'd an app I've been working on up into my webapps/app-name directory. However the website is still using the default 'hello_world' rails app in that directory (which was created from the control panel). I cannot work out how to get nginx to use the app I uploaded rather than the 'hello_world' default. If I delete hello_world and point nginx/conf/nginx.conf server root to my new app I still get 404's. If I simply rename my app hello_world I get the error: 'Ruby (Rack) application could not be started'

Any help would be greatly appreciated!

Cheers, Mike