Image upload don't work fine after upload

Hi guys, I just made an upload of the wordpress MU for wordpress 3.0, but image upload not work more.

I don’t believe that problem is related with my CHMOD server because before work fine, and now work fine with other sites non multisites.

The images url direct for main domain see foryouself:

https://webluz.net/showcase/entrepeneur_demo/files/2010/07/cc.jpg
https://webluz.net/showcase/feb/files/2010/07/cc.jpg

I think that .htaccess need some change, thanks if you may help me.

My .htaccess are >>

RewriteEngine On
RewriteBase /showcase/

#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>