Building a dynamic menu with Drag and Drop Interaction

Hello,

I've got some 1980's-1990's videos that I must use in a current course. To have some interactivity and some fun, I've created a drag and drop interaction, where the learner drags VHS tapes to a VCR player and a lightbox slide appears with a short video. This is not a quiz but instruction. After the 5 VCR tapes are dragged to the VCR player, I want the learner to advance to a slide layer to receive further instruction. 

I don't want a Submit button to submit the interaction, as this is not a quiz. So I assigned a variable to increase in value each time the video lightbox slide's timeline starts. After the variable increases to 5, the interaction should be submitted. But nothing happens after that. I've also tried removing the variable and just trusting the interaction of the drag and drop, but it's still not advancing to a slide layer or slide. 

Please help