ember.js tutorial: is really working Mirage addon?

Following the ember.js tutorial, I get stuck in this step:

http://ift.tt/2oz8amn (the exact part when Mirage add-on is used.

Is there anything else to do to get shown the Mirage data included in the mirage/config.js file?

No matter what I change in that file... that I'll keep having the data served from the previous app/routes/rentals.js.

Did anyone have the same problem?