Tried this too
In desperation, I deleted both the cart and books file where I had added the add to cart buttons. After recreating these .php pages, I entered the code just as instructed. Nothing. Because I have a deadline, I'm moving forward without the images on the shopping cart page. I figure I can go back once I've figured out what's wrong and add the images code later. In the meantime I really do want to know how to accomlish this.