Every time I try to put a puzzle piece into the frame, it won't stay there and just slips back down into the jumble of pieces. Can anyone help with this?

When click on the piece and begin dragging it do you see a circle with a line through it over the image? The symbol would look like this, but in black:

No, the symbol isn't showing up.

When you put it over a spot on the board do you see a yellow background right before dropping (unclicking) the piece?

Yes! I've discovered that was my problem...I was moving the piece to far to the edge. Thank you a bunch for your help!!

Your welcome. :) Glad you managed to figure it out. I had the same problem when I first attempted the puzzle (among other ones with it glitching on me). Good luck with the plot!