After it says "success" or a blank white screen, please click on your back arrow on your device and go back to the main screen where you logged in to Facebook's API. If clicking back does not take you back to the initial sign in sheet, close out of TweetCaster and go back in to where you initially login to Facebook through TweetCaster. Once you are on the initial screen to login to Facebook, please click on the statement "Try the alternative login". This is located under the "Login" button and under where it says "forget password". Once you click on this "Try the alternative login" it will show you the same login screen. Please try and login again and try and make a post as needed.