If you use FitBit tracker with a smartphone which has been recently undated to Android 5.0 Lollipop, you might faced the same problem as me - the Fitbit app has stopped synching with the tracker.
Surprisingly there are a lot of people complaining online or even raging in putting one star rating to the app in Google Play. However, the solution which helped me: uninstall and reinstall the app, is mentioned on the FitBit Help web-site, and it takes around a minute to remove and reinstall the app.