db_addon: sometimes values aren't recalculated

[stephan-schuster]

First of all I would like to thank you for this great plugin, it has saved me a lot of time. But there is still a small problem: Sometimes the values are not recalculated and remain at 0:

The picture is taken on a tuesday at 14:35, so the values for the current week / day can't be 0. And after triggering the recalculation in the web interface the values are shown. So the plugin seems to have problems to determin, which values have to be recalculated.