Domain can't be added because already in use on another site

Hi,
Im woring on connect my domain to my Squarespace page, but I got the message that it's connected to another site. It should not be connected to other places since it's a new domain, and I cannot find out how to solve this.
the domain is: echostudio.no

For now I just forwarded it thru my registrar.

Hope someone can help me with this issue.

PEr

echostudio.no is a  Domeneshop domain but is not connected to any website. You may be able to connect it to a Squarespace site, but it would have to be managed using a  Domeneshop account. 

https://domene.shop/login

I can't find a specific guide for a Domene domain but this might help you:

Connect third party domain to Squarespace website.

yes, that's correct. Ive been using domeneshop for another domain before and this was strait forward.
I attached a file where you can see how I setup that one.
 

my problem is that I get this error using the connection guide in squarespace 

"If you see a message that says "This domain is already connected to another Squarespace site," check your other Squarespace sites to find where the domain is connected. Then disconnect it from that site."