Images Are Not Visible

I have the gallery on my page with pictures, but they come up looking like white tiles instead of the actual pictures. If you click on one to look at it close up you can see it, but other than that, they aren’t visible from the gallery itself. Is there something I am doing wrong?

Here is what it looks like:
http://blog.meettheartistsandartisans.com/fine-art-exhibitors/

And here is the code I put in as well:
[go_gallery cat=’paint, mixed, sculpt’ size=’small’ gap=20 border_size=10 limit=12 menu_show=1]

https://wordpress.org/plugins/go-gallery/