Is my jigsaw puzzle logic correct?

So I'm trying to build a jigsaw...have read dozens of threads, and been working on it for several hours...but it's not quite working. Is my thinking along the right track?

1. Broke image up into 15 seperate PNG images. (Curvy pieces, not rectangles)

2. Imported images to storyline and moved them around to make the puzzle.

3. Duplicated the puzzle and made all pieces transparent.

4. Set drag and drop to move coloured piece to drop on corresponding transparent piece.

Seems to work for the majority of pieces, however, a few pieces just seem to drop into odd positions. Is my build logic right? Any other ideas or tips? Thanks.