Okay, I've changed the coding per your instructions. Now, when I click on a hat, say the first one, and add it to my cart, the thumbnail shows up! Problem is, when I Continue Shopping, and then go add more hats of a different style, their thumbnails DO NOT show up.
I've attached a screen capture, and once again the cart.php code. Every single hat has a thumbnail attached to it. I went to each cart Add to Cart object, and selected the bindings tab, and in the thumbnail column put the exact name of the picture (i.e., logohat3_tmb.jpg, or Hatphotoshop3_tmb.jpg).
The only hat that shows up is the first one As you can see by the screen capture.