Issue with www.domain name and justdomain.com

I have the plugin set up and I have the IP added to the domain that I am mapping. When trying to access the site, it works when you type http://www.thedomain.com but doesn't if you just type the domain.com and not add the www. When you do that it pulls up my main site. What could I be doing wrong?

The is the site http://www.jdsvisionaries.com