Thanks!
I changed the code to look like that, work’s good so far.
if ( bp_has_members( ‘type=active’ ) ) :
$count=0;while ( bp_members() ) : bp_the_member();$count++;
$output .= section_members_li();
if ($count % 6 == 0) { $output .= ‘<li class=”two columns mobile-two member”>MY AD‘; };
endwhile;
endif;