“more” is NOT for multipage psts!
“more” is just for that: cutting the text where it is inserted and showing the rest in the single post view.
The “more” works only on so-called multipost views (templates) like index, archive, search…
Paginated posts (if you mean that a long post is broken in more ‘pages’) uses a different tag: <!--nextpage--> http://codex.wordpress.org/Template_Tags/link_pages
Warning: the tag has been deprecated since WP 2.1.