Remove the index.php htaccess

[eluser]CodeIgniter Web[/eluser]
Hi friends,

My folder structure,

www
codeigiter
system
user_guide
js
css
index.php
admin.php
.htaccess

system/application/config/config.php

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

MY .htaccess
RewriteEngine on
RewriteCond $1 !^(index\.php|images|css)
RewriteRule ^(.*)$ /codeigniter/index.php/$1 [L]

But 500 Internal Server Error . Please guide me the remove of index.php