No redirect to domain in Multisite network

I have followed this tutorial:
https://premium.wpmudev.org/blog/how-to-map-domains-with-the-wpmu-dev-domain-mapping-plugin/

I have a dedicated IP.
I have set up a Multisite network (subdomains) with three websites:

en.weydelandkaas.nl - mapped to - weydelandcheese.com
cn.weydelandkaas.nl - mapped to - weydelandcheese.cn
weydelandkaas.nl - main domain.

When I enter cn.weydelandkaas.nl it redirects fine.
But when I enter en.weydelandkaas.nl it doesn't redirect. I get an error of server problems: http://en.weydelandkaas.nl/cgi-sys/defaultwebpage.cgi

Weird, I have checked all the settings.
Can you help me?