Drag/Drop Multi Option Auto Submit

So i have built a Drag Drop exercise.

I have 2 drop zones and 15 drop objects.

8 drop in the first zone, 7 in the other. Each drop zone only takes up to 3 in each.

Each zone has been set to accept the only the objects from the corresponing group of 8 or 7 drop objects. They are also set to count 3 so only 3 are accepted.

I also have set the correct ansers, and set to autosubmit.

I have set on correct to display a caption.

I want to display a caption once the zones have accepted 3 drop targets each. But doesnt seem to be working.

It works if all the answers can be dropped in, but i need to limit to 3 per zone (and they need the list of 15).

Any ideas??