Domain Mapping Plugin - how to point domains to a multi-site hosted on a sub-domain

I have more than one multi-site under one shared server set up. I have one main domain that my server is under, and I have several Sub-Domains, 2 of which I have set up a WordPress Multi-Site install on in addition to the WP Multi-Site install on the main domain name, so three in total.

With the domain mapping plug-in, I have been able to get it working for the sites that are under the main URL install, but I have not been able to under the sub-domain installs. When I go to one of the URL's that I am hoping will be pointing to a wordpress site that is on one of my sub-domain installed multi-site set ups, it's taking me to the main account URL everytime (the URL that the server is set up under, not that particular network of sites home, which is a sub-domain).

So my question is, what am I doing wrong in the DNS A Record set up on my host site.

how can I get them to point to the sub-domain then the IP of the site rather than just going to the main domain that I have hosted there. What is the NAME I should use for the A Record?

localhost.nameofsite.com < is not working for sites under the sub-domain, but is working for sites under the main hosted domain.

I have tried: localhost.subdomainsiteurl.nameofsite.com and subdomainsiteurl.nameofsite.com and neither has worked.

Any suggestions?