Registration redirect on sub-site link incorrect

Summary

When I try to register a user from a sub-site it redirects to the mainsite withwout the www protocol infront.

I am using /subdirectories and not subdomains

The link is perfect generated: http://www.mysite.com/subsite/wp-login.php?action=register

When clicked it resolves to

http://mysite.com/wp-signup.php (and results in a “Error establishing database connection” error)

wp-admin and wp-login have no problems.

My .htaccess looks like this:

‘# BEGIN WordPress
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

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

Any ideas where I went wrong?

I have correctly specified

‘define( ‘DOMAIN_CURRENT_SITE’, ‘www.mysite.com’ );’ in wpconfig.php as well