[dieKetzer]

the problem is in the second image.
- you will need to specify a page for 'rund ums forum'. if you do not, default sub nav links will load.
- you will need to set a 'this_script' for 'rund ums forum', or else the tab will not 'select', and the sub nav links will not appear.

for an experiement, try to link your rund tab to /subscription.php, and set the 'this_script' to subscription. you should see your rund tab select and your sub links appear.
for this tab type to function properly you need to link it to a proper page.