Yes I did. I made added the new nameserver in a record. I added them in Host Summary, then pointed the domain to this new nameserver.
After this didnt work i tried something else. I have reset all the abouve changes. Now i am simply pointing the domain to an already established nameserver on ISPConfig. (I use this for another domain, actually I wanted those domains to be complety sepertated, hence I tried to add another nameserver)
But I am getting the same result. The nameserver does not properly resolve the new domain. Why is this not working? Everything in ISPCOnfig is set up 100% correctly. At least the things I can see inside the graphical interface...