adding a subdomain.

I want to add a subdomain that is identical to our main website. I would like to FTP everything over, however i tried doing that and when I attempt to go to login page it switches me to login in page for my main domain admin login(if that makes any sense.)

Basically I created a subdomain: perry.maxeysbailbonds.com I then ftp over the contents of my main site so as to make it an exact replica.

Problem is when go to the login page for that subdmain it take me to login for my main domain.

What am doing wrong…. which files should I not transfer? or is there a tutorial on how to do this?