pagination – How to get "nexepagelink" and "previoiuspagelink" in wp_link_pages?

I'm trying to have a pagination in my pages, so I use this default option:

    & # 39;
& # 39 ;, & # 39; after & # 39; => & # 39;
& # 39 ;, & # 39; link_before & # 39; => & # 39;& # 39 ;, & # 39; link_after & # 39; => & # 39;& # 39 ;, & # 39; next_or_number & # 39; => & # 39 ;, number & # 39; separator & # 39; => & # 39; & # 39; nextpagelink & # 39; => __ (& # 39; Next page & # 39 ;, & # 39; here-a-universal-one & # 39;), & # 39; previouspagelink & # 39; => __ (& # 39; previous page), & # 39; behold-universal-one & # 39;), )); ?>

works everything except "nextpagelink" and "previouspagelink". No matter what I use, no next or previous text is visible. Of course, there is more than one page break. WordPress 5.1

Ideas why?