Incorrect domain mapping. Can't find style.css

Question

My problem is most likely related to setup. I can't seem to figure it out.

I have a domain example.com, which has a subdomain mysite.example.com I installed the WordPress MU Domain Mapping plugin, and set up a mapping for mysite.com

Now if I use mysite.example.com the theme is fine, but if I access mysite.com, it can't find style.css

Here is the content of my .htaccess(as I suspect it has something to do with rewrites):

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

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

Do you have any ideas what might be wrong?