Permalink not working

Hi there,
I know that this is a common issue but actually I tried everything I found around in the web and nothing help me.

If I use the custom way for the permalink I’m forced to have the “index.php” on my url because without it doesn’t seem to work.

So actually this is my .htaccess:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /somatologia/
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /somatologia/index.php [L]
</IfModule>

# END WordPress

This wp installation is done in a subfolder. The link is this:

http://www.eterniinrete.it/somatologia/

I used this custom code for the permalink:

/index.php/%post_id%/%postname%/

and so I can navigate the pages but with this “index.php” in the url.

What to do to avoid the index.php? If i use this code:

/%post_id%/%postname%/

all the link redirect me to the home page.

Thank in advance.