We\'ve just changed to Twitter api 1.1, and now Tweeting doesn\'t work & returns an error \"The remote server returned an error: (400) Bad Request.\" Researching on SO
I had exactly the same problem:
This is exactly what you need to do here:
Authenticate and request a user's timeline with Twitter API 1.1 oAuth
I have created a project for this at : https://github.com/andyhutch77/oAuthTwitterTimeline
It also includes an MVC, Web app and console demo.