Send Drag and Drop Source to original position - Not working

I just posted this to advanced topics but I now realize I should have posted it here...

I'm getting great answers here, so....

I've created a drag and drop in which student drags three different types of fractions into the correct drop targets.

I've checked 'send drag source to original position but the drag object stays wherever it is put. I would like it to pop right back immediately if dragged to the incorrect drop target.

Is there something else to be done to make the drag source pop right back to its original position immediately if not dropped into the correct drop target?

Thanks.

Daniel.