why can’t i add a new DC to my domain?

i’m trying to add a new DC to my domanin that only has one DC but i get an eror that says “the operation failed becouse:
Faild finding a suiteable domain controller for the domain (and my domain name”
“the sepecified Domain either does not exist or could not be contacted”

the server that i’m trying to promote is allready on the domaina as a stand alone and sees and contacts the DC very fine and gets all the data from it, i just can’t figy=ure out why i get this massege. I even made the server a delegted trusted server in AD.
and downloded SP2 but it hasn’t helped.

P.s. i’m in native mode
thank you for your help in advance