There are 2 issues:
1: To zoom an image, one image has to be larger than the other. Your two images are the same size. Look carefully at the href and src here and you'll see they reference the same image:
`<a href="http://images.cdn.bigcartel.com/bigcartel/product_images/142875802/max_h-1000+max_w-1000/House-By-The-Sea-A32.jpg" class="MagicZoom" rel="zoom-width:450px; zoom-height:450px"><img src="http://images.cdn.bigcartel.com/bigcartel/product_images/142875802/max_h-1000+max_w-1000/House-By-The-Sea-A32.jpg" alt="Image of House By The Sea"/></a>`
Either make your main image (src) smaller in width/height or make your large image (href) bigger in width/height.
2: You must also fix some CSS. The following CSS rule in your stylesheet is reducing the zoom image to the width of the zoom window.

To display the image at its original (larger) size, add the following CSS:
.MagicZoomBigImageCont img { max-width:none !important; }
3: Not required, but because this particular image zoom is so large, it would look good enlarged to full-screen. That's possible on click if you use Magic Zoom Plus instead of Magic Zoom.