customizing the chart tooltip

[Gal]

Hi!

I'm trying to add another field to a chart tooltip, that is not a part of the chart itself, but appears in the query.
the only way I could find is by editing one of the custom labels of the chart components, defining it as a report expression, and adding a title and the field.

My problem is that I have a stacked bar graph. I need the tooltip to change within each segment on both axis. For values defined within the chart, those values do change. For the additional field that is not defined within the chart, it only changes on one axis, but not both.

How can I solve this problem?