Wordpress pagination gives 404 error -

i have following situation ,

in wordpress 3.5 installation have page called "blog" , assigned posts page in settings->reading can show posts in domain.com/blog/

the problem gives me 404 error page in when try paginate posts url domain.com/blog/page/2 gives me 404 error page

i think rewrite problem added following line functions.php

add_rewrite_rule('blog/([^/]+)/page/?([0-9]{1,})/?$',  'index.php?name=$matches[1]&paged=$matches[2]', "top"); 

but nothing happend