Can't login with custom domain

Hi,

I have installed the domain mapping plugin and I am able to map an external domain to a sub blog of the multisite install. One thing though, when I try to login with the newly mapped domain, it keep redirecting me back to the login page.

for example,

i have mapped a domain http://holisticwp.com to http://blogwp.blogcademy.com.

When i go to http://holisticwp.com/wp-login.php, it doesn't me to login. Instead it keep redirecting me to the login screen.

Any help will be appreciated.