Cannot deploy rails 3.0/datamapper on heroku cedar

I'm trying to deploy an new rails 3.0/datamapper application on heroku cedar.

Despite I can run the console and do successful "app.get ''", every request gives the following error in the logs with no backtrace:

2011-06-12T11:31:04+00:00 heroku[router]: Error H10 (App crashed) -> GET empty-samurai-701.herokuapp.com/ dyno= queue= wait= service= bytes=

A weird thing I noticed that can be related or not to my problem is that I needed to run

heroku run script/rails console

instead of

heroku r开发者_C百科un console

It was simply because I didn't add the rails gem into my Gemfile.