Post Pagination Issue

I am experienceing a prblem in trying to break up a long post in multi pages. tried just using the <!––nextpage––> tag but it was either not showing on post or displaying to the right of the content.
I added the following code to the loop-index.php:
$avia_wp_link_pages_args = apply_filters(‘avf_wp_link_pages_args’, array(
‘before’ =>'<nav class=”pagination_split_post”>’.__(‘Go to page:’,’avia_framework’),
‘after’ =>'</nav>’,
‘pagelink’ => ‘<span>%</span>’,
‘separator’ => ‘ ‘,
));
wp_link_pages($avia_wp_link_pages_args);

This seemed to work to put the pagination after the content but it also is now showing the regular “pages: 1,2…” next to it so there are now two pagination elements showing. What do I need to rem out or change so that I just have the pagination showing after the post content.
Thanks.