Improve the Leverage browser caching

I want to increase the score of our website on http://developers.google.com/speed/pagespeed/insights/.

The current score is 71/100.
It shows the item to be fixed is Leverage browser caching.

To fix the same in have included the following in the configuration file of nginx.
location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
expires max;
log_not_found off;
}

But still the score is not improving and it still shows the item to be fixed - Leverage browser caching.

Please help.