"Authentication failure: no authorization header" when using EY ApiHMAC to connect

In the tutorial (https://github.com/engineyard/chronatog#verifying-requests-from-engine-yard), you mention using the ApiHmac for connecting to your EngineYard service.

class Engineyard::CustomersController < ApplicationController

```
use EY::ApiHMAC::ApiAuth::LookupServer do |env, auth_id|
api_creds = YAML::load(File.open("#{RAILS_ROOT}/config/engineyard.yml"))

(api_creds["auth_id"]== auth_id) && api_creds["auth_key"]
end
.....
```

I keep getting "Authentication failure: no authorization header" when I access my URL directly in my browser though. Is this normal ?