i want to add a custom field in photo upload function

hi i want to add a custom field in photo upload function but when i try to add the field of name it did not work .How could i solve this problem.here is my code

Cloud.Users.login({
        login : Ti.App.Properties.getString('Email'),
        password : Ti.App.Properties.getString('Password'),
    }, function(e) {
        if (e.success) {
            Cloud.Photos.create({
                photo : Titanium.Filesystem.getFile('index.jpg'),
                fields : {
                    Name:'shahab'
                }
            }, function(e) {
                if (e.success) {
                    var photo = e.photos[0];
                    Ti.API.info('Success', 'Success:\n' + 'id: ' + photo.id + '\n' + 'filename: ' + photo.filename + '\n' + 'size: ' + photo.size, 'updated_at: ' + photo.updated_at);
                } else {
                    Ti.API.info('Error:\n' + ((e.error && e.message) || JSON.stringify(e)));
                }
            });
 
        };
 
    });