Cannot read property 'Mixin' of undefined Ember Validation

I am using yeoman generation of ember app.

I've installed ember-validations using the following line in dependencies, bower.json file.

"ember-validations": "http://builds.dockyard.com.s3.amazonaws.com/ember-validations/ember-validations-latest.js"

Then I ran

bower install

This is how I am using the validator in the controller

Client.UsersCreateController = Ember.ObjectController.extend(Ember.Validations.Mixin);

But when the server starts the following error appears in the console:

Cannot read property 'Mixin' of undefined