I'm not following you. You say you have some arrays configured on the enclosure and you can't see them? So when you launch ACU you can see the arrays you have created of the disks in the enclosure?
You say you tested the card - do you have the card and the enclosure working together to show your arrays in another server?
"I read somewhere, that you can't share storage of a DAS with a Server, as apart of an array..? Is this not the case?" - What this means, is that if you have an array on the internal disks in the server, you can't put those disks and the disks in the enclosure in the same array.