How can I use an item according to ID number? (inventory)

I have an inventory, a slot widget and an item in the inventory that I want to it to interact with another actor (a box) standing in my level when I press the mouse on the item’s slot.

It all works up to this point, but I want other objects in the inventory to not interact with the box. I tried various things based on “doors with key” tutorials and a lot of tweaking but nothing works correctly. I am sure this is something small that I’m missing. Any ideas what it could be?