301 htaccess ignored

I don’t get it. I tried everything, but my redirection from non-www to www just won’t work. The htaccess is correct, I tried a few variants and at the moment it looks like this:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^dreadfactory\.de$ [NC]
RewriteRule ^(.*)$ http://www.dreadfactory.de/$1 [R=301,L]

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

# END WordPress

It does not seem to matter where I place the rewrite, it is simply ignored. Well, not ignored, but the redirection seems to take place somewhere else. The redirection code is 302 eventhough I specified to use 301.

I deactivated cache plugins to see if they were messing something up, but neither WP Super Cache nor WP minify seem to be responsible for the problem.

Othe redirects (from .net to .de) are using 302 too, even if I put in the 301 part…