I can't sign in

I go to the "Servers" tab, I click on a server, then It shows me that "Sign in to Xbox Live now!" I click on the button. Then, *NOTHING HAPPENS*. Also, I can't play my worlds (local, not downloaded) The main menu "Sign In" button isn't working too. (I don't know why. I tried again then it was the same result, sorry if I can't upload a screenshot here)