Emberjs Fixture adapter queryFixture not working

I have been having an issue implementing the queryFixtures function in Emberjs-Data. I have the following code to define the Store:

App.Store = DS.Store.extend({
revision: 12,
adapter: DS.FixtureAdapter.extend({
    queryFixtures: function(fixtures, query, type) {
        console.log(query);
        console.log(type);
        return fixtures.filter(function(item) {
            for(prop in query) {
                if( item[prop] != query[prop]) {
                    return false;
                }
            }
            return true;
        });
    }
})
});

My Model looks like:

FireSurveyApp.User = DS.Model.extend({
  userId: DS.attr('number'),
  username: DS.attr('string'),
  password: DS.attr('string'),
  FirstName: DS.attr('string'),
  LastName: DS.attr('string')
});

When i try to get the fixture data out i am using the following code:

var returnUser = this.store.find("User",{ username : "Ted"});

The function will return undefined, Is there a different way that i should be calling the queryFixtures function?

Thanks in advance.