Unfortunately, quite a lot Android devices out there do not support gathering accelerometric data (sleep tracking) with screen-off. This is duo to a bug which is on 100% of devices with Android version 1.6 to 2.3.4, on many +2.3.5 device and even on several devices with +4.0. We are doing an automated detection of whether you device is screen off tracking capable or not. In case we detect it isn’t we turn screen on automatically during sleep tracking in order to keep tracking functional.
If you think we did detect your device incorrectly you may try to re-detect using the following process:
1) Go to settings misc.
2) See what does the option “Screen-off tracking” say.
3) You can try to reset this option by clicking on it and confirming.
4) Then turn off the screen, wait for ~3 minutes and turn it back on.
5) See what does the option say now. If it says the screen-off tracking is supported, the next tracking you run should automatically turn off the screen. If it, on the other hand, says it is not supported, then your phone likely does not allow sleep tracking with screen off. You can try to use an option lower in the menu “Force screen-off tracking”, but beware it may result in sleep tracking and smart wake up malfunctioning