Tow domain for One site

Hi,

At the first Thanks a lot and

Ive a site unity3d.ir and Im going to use another domain (means u3d.ir) for this site,

ex:
blog1.unity3d.ir
blog1.u3d.ir

I used the parked domain but when i use u3d.ir , it redirect me to unity3d.ir/register page,

*server panel is cpanle

plz Help me , and sorry for my weak en language