Key of root node by clicking child

Hi there,

my hierarchy-scenario as follows:

Key               Text

12/3              AAA

     32/6               aaa

     47/9               bbb

33/6              BBB

     54/8               ccc

     87/6               ddd

In my crosstab selection is enabled and I need to identify the key of the root node when I click on a child.

E. g.: Click on "47/9 bbb" --> I need the key "12/3" of text node "AAA".

I tried to to work with "forEach" in combination with the corresponding characteristic "profit center" but of course I only got the key of the characteristic itself but not the one of the text node.

It would be great if anybody has got a hint for me.

Best regards

Mark