Cloudboost - Register User Error

Question

I'm using the example from your quickstart section on your website to register a user, problem is, it is throwing back an error. Did I miss something? See below for the error.

Error: Request failed with status code 400 - https://api.cloudboost.io/user/ohoydfjlnmnf/signup

CB.CloudApp.init('ohoydfjlnmnf', '********-3*9b-4**b-9***-a**b**2**5*1');

//Registration
var user = new CB.CloudUser();

user.set('username', 'NEWUSER');
user.set('password', 'PASSWORD');
user.set('email', 'EMAILADDRESS');

user.signUp({
    success: function(user) {
        //Registration successfull
        console.log(user);
    },
    error: function(error) {
        //Error in user registration.
        console.log(error);
    }
});