Can't get parked domain to redirect to subsite with MU Domain Mapping

I am trying to redirect the domain http://bankstel-theater.nl to a subsite, url: http://cinereus.nl/bankstel-theater.

I use DirectAdmin, and I have set up a domain-pointer for bankstel-theater.nl, within that pointer, the A-record points to the server IP. When I visit http://bankstel-theater.nl it redirects to http://cinereus.nl. According to my hosting provider these settings are correct.

I installed the MU Domain Mapping Plugin, and followed the instructions for setup. http://cinereus.nl/bankstel-theater is set as my primary domain. I want users to see this url when they visit http://bankstel-theater.nl. I tested if there was a difference if I made http://bankstel-theater.nl my primary domain, but It doesn’t change a thing.

Now when I visit http://bankstel-theater.nl/bankstel-theater, it redirects to http://cinereus.nl/bankstel-theater. I need to get rid of the /bankstel-theater at http://bankstel-theater.nl, so when users visit http://bankstel-theater.nl it needs to redirect to http://cinereus.nl/bankstel-theater

Yes, the domain in the address bar does not need to stay http://bankstel-theater.nl, because bankstel-theater is a ‘product’ of Cinereus, and I want users still to see that bankstel theater belongs to cinereus.

What I actually want is a redirect from http://bankstel-theater.nl to http://cinereus.nl/bankstel-theater. But I can not seem to get this done.

I also tried some rewrite rules inside my .htaccess, but they also not seem to work.

RewriteCond %{HTTP_HOST} ^bankstel\-theater\.nl [nc]
RewriteRule ^bankstel-theater\.html$ http://cinereus.nl/bankstel-theater [R=301,NC,L]

RewriteCond %{HTTP_HOST} ^bankstel\-theater\.nl$ [OR]
RewriteCond %{HTTP_HOST} ^www\.cinereus\.nl\/bankstel\-theater$
RewriteRule ^/?$ "http\:\/\/.cinereus\.nl\/" [R=301,L]

What am I doing wrong here?