Can't learn any more lessons or take tests
Every time I try to learn a new lesson the message comes up "Could not connect to Duolingo. Try starting the session again." - which does nothing. And when I try to practice weak skills "There's nothing to practice right now. Try doing some lessons first." I've just passed the third checkpoint in the Spanish tree and at least a third of my lessons aren't gold, so could someone help me out here?
Edit - Forgot to mention, I am using the iPhone app.