Update your phone software to PR1.2.

With PR1.1 (or earlier) the charging indicator light may not always flash even though the phone is charging properly. This is a software related issue and improvements are available in PR1.2. The improvements are included also in PR1.1.1 device software version available for certain regions (Middle-East and Africa regions).If the charging indicator is not flashing, you can check the charging status in the status area at the top of the screen. Starting from phone software PR1.1 you can see the charging indicator also on the lock screen.