I am attempting to to obtain my WordPress web addresses to become lowercase, however the following code does not appear to become working...

RewriteEngine On
RewriteBase /

RewriteMap tolower int:tolower
RewriteCond $1 [A-Z]
RewriteRule ^/(.*)$ /${tolower:$1} [R=301]

RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

</IfModule>

You should use the module mod_speling for PHP (you have to load it first) and also the CheckCaseOnly on|off option inside your .htaccess file.