.htaccess not removing file extensions

So here is the link in question: http://cybergamegear.com/cards-for-crypto.html

The setup of my .htaccess file is as follows:

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html
ErrorDocument 404 /404.html

So it should be removing the .html part, but when you navigate to the link, it errors: http://cybergamegear.com/cards-for-crypto

Any thoughts or suggestions?