uhttpd config, index file, php vs. html

Hi, another time here because my old problem become my new problem...the situation:

/www folder is like original, with the index.html that works properly with the yun control page (I can connect using http://yun.ip/)

/www/keystore_manager_example/ have a index.html that doesn't work (I can't connect using http://yun.ip/keystore_manager_example but I can by adding /index.html)

/www/sd/ have a index.php that works properly (I can connect using http://yun.ip/sd/)

the uhttpd config:

        # Index file to use for directories, e.g. add index.php when using php
        list index_page         'index.html'
        list index_page         'index.php'

the command uci show uhttpd tells me:

uhttpd.main.index_page=index.html index.php

Why the index.html in the dir keystore_manager_example doesn't work ?