Cannot remove index.php

[eluser]Unknown[/eluser]
When I try to remove index.php
and access controller: mysite.com/admin
I keep getting Internal Server Error.

.htaccess

Code:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /code/

RewriteCond %{REQUEST_URI} ^system.*
RewriteRule ^(.*)$ index.php?/$1 [L]

RewriteCond %{REQUEST_URI} ^application.*
RewriteRule ^(.*)$ index.php?/$1 [L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L]
</IfModule>

Site config

Code:

<Directory /home/mysite.com/public_html/>
Options Indexes Includes FollowSymLinks MultiViews
AllowOverride AuthConfig FileInfo
Order allow,deny
Allow from all
</Directory>

config

Code:

$config['index_page'] = '';
$config['uri_protocol'] = 'REQUEST_URI';