[Plugin: W3 Total Cache] Copying the given code in .htaccess of Multi-site instalaltion

Hello !

I have just installed the plugin on a Multi-Site enabled installation. There was 4 codes mentioned on w3Toal cache plugin page to be copied into .htaccess file. I have copied the 3 codes

The fourth code is showing like this :

The required directives for fancy permalinks could not be detected, please confirm they are available:

RewriteEngine On
RewriteBase /

#uploaded files
RewriteRule ^(.*/)?files/$ index.php [L]
RewriteCond %{REQUEST_URI} !.*wp-content/plugins.*
RewriteRule ^(.*/)?files/(.*) wp-content/blogs.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteCond %{REQUEST_URI} ^.*/wp-admin$
RewriteRule ^(.+)$ $1/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule . – [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-.*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

<IfModule mod_security.c>
<Files async-upload.php>
SecFilterEngine Off
SecFilterScanPOST Off
</Files>
</IfModule>

I have checked my .htaccess file and can see this default code for multi-site installation :

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ – [L]
RewriteRule . index.php [L]

I think I would get problems if I copy this and remove the default one. Can you please help me to resolve the issue?

WordPress version : 3.1.1
Multi-Site enabled ? Yes
Buddypress enabled ? No , But will install in future

Thanks !