Add on styles are not working

Dear Simplest Gallery,

Thank you for making such beautiful gallerys.

I have a question regarding the add on styles. On one of my
pages I have made http://www.robinhood-fotografie.nl/?page_id=607 i am trying to change the add on style.. unfortunatly they do not work. I also tried to change the setting to use UseWPGalleryDefault JQuery but it will give an error message on the fullpage! The HTML check does not show any error in the gallery.. is there something else I can try?

Thank you for your response!

Richard

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