How to use getActivityinfo() and getSunset()

Hi guys,
I would like to get sunset/sunrise time for display on my watchface.
I have made the source code below, but currentPosi is always null in simulation, so I can not get sunset time.
What is missing to do this?
 
        var date = new Time.Moment(Time.today().value());
        var actInfo = Activity.getActivityInfo();
        var currentPosi = actInfo.currentLocation;
        if(currentPosi != null){
            var sunset = Weather.getSunset(currentPosi, date);
        }