I created a Rails application, using Rails 4.1, from scratch and I am facing a strange problem that I am not able to solve.

Every time I try to deploy my application on Heroku I get an error 500:

```
Missing `secret_key_base` for 'production' environment, set this value in `config/secrets.yml`

```

The `secret.yml` file contains the following configuration: 

```
secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>

```

On Heroku I configured the "`SECRET_KEY_BASE`" environment variable with the result of the `rake secret` command. If I launch `heroku config`, I can see the variable with the correct name and value.

Why am I still getting this error?