Maps but get my main domain in url

Help!

I set up the domain mapping plugin… it works technically… I have multisites set up as sub directories…

ex:

my main site could be “mymainsite.com” I added a second site called “mysecondsite” which is site id #2 … I add “mysecondsite.com” to map to site id #2 (mysecondsite) … so it works, but it won’t load “mysecondsite.com” but will load http://mymainsite.com/mysecondsite … why won’t it load mysecondsite.com since I’ve mapped the second site ( id#2 ) to this domain… ???

http://wordpress.org/plugins/wordpress-mu-domain-mapping/