Touch set global Variable with component variable


i have an basis gv called TabNr and seperate components.
Inside this components touch event should change the TabNr to an specific value. This is generally working.
But if I try to use component variable instead of an specific string it will set to nothing. If I use an basic gv it will work.

Did I anything wrong, or is it not working with component variables.

Alternatively i tried with the mindex formula which is also not working.