MongoDb and Symfony2.4 file not stored in Gridfs

I implemented a file upload function with a link to this link http://www.slideshare.net/mongodb/mongo-db-bangalore-2012-15070802

But the file is not saved in gridfs.

I did some research for the same, and also referring to this blog post http://php-and-symfony.matthiasnoback.nl/2012/10/uploading-files-to-mongodb-gridfs-2/

But then again, unfortunately, I’m stuck with this issue since the last 15 days

Please, help.