Removing index.php from URL

[eluser]Mohammed Zayan[/eluser]
I use this code in .htaccess file

Code:

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteBase /www/zayanit.com/zayan/

    #Removes access to the system folder by users.
    #Additionally this will allow you to create a System.php controller,
    #previously this would not have been possible.
    #'system' can be replaced if you have renamed your system folder.
    RewriteCond %{REQUEST_URI} ^system.*
    RewriteRule ^(.*)$ /index.php?/$1 [L]
    
    #When your application folder isn't in the system folder
    #This snippet prevents user access to the application folder
    #Submitted by: Fabdrol
    #Rename 'application' to your applications folder name.
    RewriteCond %{REQUEST_URI} ^application.*
    RewriteRule ^(.*)$ /index.php?/$1 [L]

    #Checks to see if the user is attempting to access a valid file,
    #such as an image or css document, if this isn't true it sends the
    #request to index.php
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php?/$1 [L]
</IfModule>

<IfModule !mod_rewrite.c>
    # If we don't have mod_rewrite installed, all 404's
    # can be sent to index.php, and everything works as normal.
    # Submitted by: ElliotHaughin

    ErrorDocument 404 /index.php
</IfModule>

and make the base_url in the config file

Code:

$config['base_url'] = 'http://www.zayanit.com/zayan';
$config['index_page'] = '';

in autoload file

Code:

$autoload['helper'] = array("html", "url");

but I can't use any method in the controller unless I write index.php in URL
like this
http://www.zayanit.com/zayan/site/contact
http://www.zayanit.com/zayan/index.php/site/contact

Where is my wrong?