Template problems [[product_main_image]]

I’m having a problem with the wplister template using the tag: product_main_image

This is the result I have on ebay: item

1) In practice, do not resize the photo by overwriting part of the template’s graphics.

2) I also tried using the tag: product_thumbnails but it does not produce any effect (you see nothing).

Why is this happening?

Thanks for the answers