Math with items from array

Hi there,
I am quite new to Grafana, so sorry if this question is very obvious.
I need to build a dashboard with data counts in source and target locations and show the difference. In Query inspector, I see that I receive two items in the array and the last one is shown on the panel, but for some reason when I’m calculation the difference ($A-$B) the result is not shown. Any ideas why?

Grafana v8.3.3

welcome to the :grafana: forum, @iho01

can you please follow these steps to share your raw unformatted data? for both queries? That way, the community can try and mock up your problem :+1:

Hi @mattabrams
I created a few panels for a different table and for some of them I see the difference in counts and for some of them, this value is empty. From the raw data, I see the difference in ‘Series joined by the time’ (see the attached video for details).