Subscription is not working like it was.

application.js

if (Meteor.isClient) {
    Meteor.startup(function(){
        Session.set('MediasLoading', true);
        Meteor.autosubscribe(function(){
            Meteor.subscribe('Medias', function(){
                Session.set('MediasLoading', false);
            });
        });
    });
}

index.js

Template.index.top10 = function(){
    if (Session.get('MediasLoading'))
        return;
    
    var medias = Medias.find({}, {limit: 10, sort: {tempo: -1}}).fetch(),
        maior_tempo = medias[0]['tempo']; // Uncaught TypeError: Cannot read property 'tempo' of undefined
}