Problems with PlugIns

Hi.

I installed and configured Domain Mapping, not bad solution. My only problem are Plugins at sub-sites. For example I use the Plugin WP Responsive Menu. Please look here whats happened (or better: whats not happend, because the Menu is not visible):

http://www.tauchen-skottevik.de

normally there must be the menu-icon on the top/right. but here is nothing. I runs without problems on the old website, with a single-wordpress-installation: http://www.wreck-explorers.com.

Other plugins fail, too. Someone how know, what can be the solution?

https://ww.wp.xz.cn/plugins/wordpress-mu-domain-mapping/