Your problem come from the IP of your web site (usualy a domain name is translated to an ID address ie: the site usr.com
as the ip address 220.127.116.11
so the same ip can host 2 diffrent domain name on the same port.
The solution to host 2 domain name with only one IP address is to change the port of the second web site (insted port: 80 "the default one" put 1000 for exemple) so after to connect to your site you'll have to type some thing like this:
(to access to your domain1)
(to access to your domain2)
The inconvenient of this, is, if you type www.domain1:1000
you will arrive on your second web site. but as far as i know it's the only solution.
I hope this will help.
PS: if some one as a better idea i'm intrested as well.