Error while processing route, Adapter operation failed Error: Adapter operation failed

While running the below code, i got an error that adapter operation failed .so any one help me to solve this problem.

(aap.js) App = Ember.Application.create();

App.Store=DS.Store.extend({

adapter:'DS.FixtureAdapter' 
});
 //App.ApplicationAdapter = DS.FixtureAdapter.extend();



App.Router.map(function(){
    this.route('posts');
    this.route('about');
});

App.PostsRoute=Ember.Route.extend({
    model:function(){
        return this.store.find('post');
    }
})