[Neos] additional content collection not visible

[Dominic Garms]

Good Morning,

I just tried to add some additional content areas to my BE:

'TYPO3.Neos.NodeTypes:Page':
   childNodes:
     'teaser':
       type: 'TYPO3.Neos:ContentCollection'
     'sidebarRight':
       type: 'TYPO3.Neos:ContentCollection'

But the child Nodes are not visible in the content area. Any idea what I 
could miss? I even copied the NodeTypes.yaml from the demo package, but 
only Content Collection (main) is visible.

Thanks for hints,
Dominic