I tried to use SignInButton control in my sl-xna project. But when I press the SignInButton, the sign in page does not rendered(If I press the Back button, the SessionChanged callback is called but the session state is still unknown. So the sign in page should have been opened but not be rendered). The code is almost the same as the sample code in SkyDrive SDK for windows phone except that my project is an sl-xna project while the sample is a silverlite project. Is there anything I need to do to render the sign in page?