How to trigger an event once all the pieces have been collected

Using Oculus Touch, I am trying to collect individual pieces. The object is to pick up 4 pieces and then drop them into a collection box. The pieces have to touch a trigger as they go into the collection box in the level. After all the pieces are collected (they have all touched the trigger box as they were dropped into the collection box) then I want a new object to spawn showing up in the level. Basically I have broken an object up into 4 different pieces/meshes. Once all 4 pieces are collected and dropped into the collection box, I want to spawn a new mesh of the pieces all put together.

I have attached my blueprint of what I have so far but it isn’t quite working. Each of the pieces touch the trigger but the final mesh never spawns. What am I missing?

Thanks, Brad