Interactive filter propositions with listboxes

[haha1234]

Hello, I am trying to find a way for users to filter data by clicking on what they want / what they don't want.

I've achieved that thanks to 3 listboxes. Two of them are linked : when the user select one parameter name, it's different possible values appears in the second list box.

My problem is due to default values : when the VI is started several times, a given value is highlighted in blue on the listbox, but when the user clicks add, this value is not reported in the filter 

Maybe I should clear the highlighted cell at VI start (but how ?). Or maybe should I work on listbox actual values instead of event "new value" ?

thank you in advance

best regards

[Artem.SPb · Accepted solution]

Change selection mode:

And you can clear selection by -1

And finally you can build string without local variables

[haha1234]

Thanks, the Val(Sgn) tips works perfectly for clearing selection at startup of the selection pop-up.