I know this is an old thread, but I'm having the same problem. I've been working with a single static button and now I've got to add another static button. The products are similar enough that I need two different thumbnails, one for each product, in the cart so people know what they're ordering. I've created a column in the cart for my thumbnails:
<td class="eC_ProductThumb"><?php echo $eCart1->DisplayInfo("Thumbnail"); ?></td>
and the column is there. I also see the Default Value box in the Add to Cart Button, and I put the name of the thumbnail in it:
Images/Shop_Thumb_FrontView.jpg
but the eCart Object still won't let me edit the Thumbnail column to read as an image. I also can't delete it, and even if I could, any Thumbnail column I could add doesn't include the "View as Image" option. Thus, when I add this item to my cart, the thumbnail column shows the name of the thumbnail, in text.
Please help. Thanks!