Pagination leads to 404

I asked this question before but i still haven’t resolved it.
Due to my previous topic being closed i’m have to ask it again.

The pagination on my website is leading to an 404 error page.
I tried to rename the “Enkelvoudig Event basis” (or in english “Single event basis”) to something else as the developer pointed out, still no luck.

Also he stated that i should use the postname permalink structure.
My current structure is like this: /%category%/%postname%/
Is that gonna make a difference? I’d rather not change it, because i really like the structures as is.

Looking forward to your reply.

The page I need help with: [log in to see the link]