multi-domains

I followed this tutorial in setting up multiple domains


http://www.h-quadrat.com/techblog/111-modx-revolution-multi-domain-context-installation-english.php

I have my main domain

www.mydomain.com

these are the sub domains
dev.mydomain.com
stage.mydomain.com

What I am having problems is in http://www.uwamp.com/ similar to wamp but much powerful. What do I have to add in the apache configuration to get it working because when i type in the URL address bar dev.mydomain.com it redirects to www.mydomain.com

I figured it out I followed this method instead.