They go in backwards, for real. Did you know that. Put + in -
Please say you knew this.
Other than that, make sure you are on the default layer (or reset the layer you are on)
Turn the brightness up. I believe the lowest setting is OFF. They may just be turned down.
Also, they have like 4 settings. On, breathing, light up when pressed, etc... press the keys to make sure you aren't in the one of those animations that only lights when pressed?