Domain Mapping doesn't show up on website backends

Hello,

I installed the Domain Mapping Plugin with some help of this post ( https://premium.wpmudev.org/wdp-un.php?action=help&id=99&TB_iframe=true&width=640&height=800 ). I can administrate the plugin in the Multisite backend, but it doesn't show up on the subwebsites. I can't map them. Do you have any idea?

Yours
Stef