How to add target line to stacked column pivot chart chart

Hi All,

I need to add target line to stacked column chart (it must be a pivot chart and not chart).
for example a line at 5 at y-axis.
i know i need to create a dummy series and change its type, but i can't figure the right way to do it

any thoughts?

thanks!

Book1.xlsx

this is what i need, but when the data is updated the target line is back to stacked column type?
what can be done?

thanks!
got it!