Portfolio items

Hi,
I can not get the lazy load function working on my portfolio thumbnails, see this page; https://graffitinetwerk.nl/portfolio/

when i check ‘Apply to post thumbnails’ al the portfolio items give a no image error.
also, i tried to exclude these items but this does not work, i tried al the classes around the image.

do you have an idea, or could you maybe take a look?
hope to hear from you!

https://www.ads-software.com/plugins/bj-lazy-load/