problem with removing index.php

[eluser]citm[/eluser]
I am new in code igniter and I have the same problem:

I've created .htaccess file and I've put it in the same root that index.php:

<code>

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

</code>

The result is 500 inernal server error

I want this structure:

http://www.mydomain.com/myclass/

and not

http://www.mydomain.com/index.php/myclass/

Thanks in advance!!!