Nginx_storage doesn't work. What am I doing wrong?

Question

Nginx

Good day!
I tried to configure nginx_storage as a permanent cache, files are proxied but not written to storage.

location ~* /get_([0-9]+)/(.*).txt$ {
        root /var/www;
        try_files /nginx-store/$1.txt =404;
        open_file_cache_errors off;
        error_page 404 = /internal_$1/$2.txt;
    }
    location ~ /internal_([0-9]+)/(.*).txt$ {
        internal;
        proxy_pass http://serv2/$1/$2.txt;
        proxy_ignore_headers "Cache-Control" "Expires" "Set-Cookie";
        proxy_store /var/www/nginx-store/$1.txt;
        proxy_store_access   user:rw  group:rw  all:r;
    }

When I physically create a file in /var/www/nginx-store/2222.txt, then by request /get_2222/name.txt I get access to it.
What am I doing wrong? Or maybe I didn’t understand the functionality of nginx_storage from the nginx manuals?
Thanks in advance.