The Hulk Mark Ruffalo has upset his bosses at Marvel Studios by breaking a social media ban and tweeting a snap of himself and co-star Robert Downey, Jr. on The Avengers: Age Of Ultron set. The movie star took to Twitter.com on Wednesday (23Apr14) and told followers that his work on The Avengers sequel had begun. He wrote, "Today was the first day of shooting 'Age Of Ultron' when all of the Avengers we reassembled (were assembled)! Awesome sight!" He added a shot of himself and Iron Man Robert Downey, Jr. and later attempted to get a photo of co-star Scarlett Johansson in character as Black Widow - but she hid her face in a robe, prompting Ruffalo to post, "Almost got her!!!" The fun quickly ended when Marvel's top brass reprimanded the actor for taking shots on set. A tweet simply read: "Maaaarrrrrrkkkkk!!" And when Ruffalo played down the drama by telling his producers, "I adore you", they responded with the tweet, "Flattery will get you nowhere! Probably. Maybe. *looks the other way*." The actor appeared to have learned his lesson - he later wrote, "I'm sorry @marvel. I will be better. I'm like your black sheep Avenger."